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Title: The Chemistry of Hat Manufacturing - Lectures Delivered Before the Hat Manufacturers' Association
Author: Smith, Watson
Language: English
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THE CHEMISTRY

OF

HAT MANUFACTURING


LECTURES DELIVERED BEFORE THE HAT MANUFACTURERS' ASSOCIATION

BY

WATSON SMITH, F.C.S., F.I.C.

THEN LECTURER IN CHEMICAL TECHNOLOGY IN THE OWENS COLLEGE, MANCHESTER
AND LECTURER OF THE VICTORIA UNIVERSITY

REVISED AND EDITED

BY

ALBERT SHONK

WITH SIXTEEN ILLUSTRATIONS

LONDON
SCOTT, GREENWOOD & SON
"THE HATTERS' GAZETTE" OFFICES
8 BROADWAY, LUDGATE HILL, E.C.


CANADA: THE COPP CLARK CO. LTD., TORONTO
UNITED STATES: D. VAN NOSTRAND CO., NEW YORK
1906

[_All rights remain with Scott, Greenwood & Son_]



Transcriber's Note: Underscores around words indicates italics while an
underscore and curly brackets in an equation indicates a subscript.



PREFACE


The subject-matter in this little book is the substance of a series of
Lectures delivered before the Hat Manufacturers' Association in the
years 1887 and 1888.

About this period, owing to the increasing difficulties of competition
with the products of the German Hat Manufacturers, a deputation of Hat
Manufacturers in and around Manchester consulted Sir Henry E. Roscoe,
F.R.S., then the Professor of Chemistry in the Owens College,
Manchester, and he advised the formation of an Association, and the
appointment of a Lecturer, who was to make a practical investigation of
the art of Hat Manufacturing, and then to deliver a series of lectures
on the applications of science to this industry. Sir Henry Roscoe
recommended the writer, then the Lecturer on Chemical Technology in the
Owens College, as lecturer, and he was accordingly appointed.

The lectures were delivered with copious experimental illustrations
through two sessions, and during the course a patent by one of the
younger members became due, which proved to contain the solution of the
chief difficulty of the British felt-hat manufacturer (see pages 66-68).
This remarkable coincidence served to give especial stress to the wisdom
of the counsel of Sir Henry Roscoe, whose response to the appeal of the
members of the deputation of 1887 was at once to point them to
scientific light and training as their only resource. In a letter
recently received from Sir Henry (1906), he writes: "I agree with you
that this is a good instance of the _direct money value_ of scientific
training, and in these days of 'protection' and similar subterfuges, it
is not amiss to emphasise the fact."

It is thus gratifying to the writer to think that the lectures have had
some influence on the remarkable progress which the British Hat Industry
has made in the twenty years that have elapsed since their delivery.

These lectures were in part printed and published in the _Hatters'
Gazette_, and in part in newspapers of Manchester and Stockport, and
they have here been compiled and edited, and the necessary illustrations
added, etc., by Mr. Albert Shonk, to whom I would express my best
thanks.

                                WATSON SMITH.

LONDON, _April_ 1906.



CONTENTS


LECTURE                                                   PAGE

I. TEXTILE FIBRES, PRINCIPALLY WOOL, FUR, AND HAIR           1

II. TEXTILE FIBRES, PRINCIPALLY WOOL, FUR,
    AND HAIR--_continued_                                   18

III. WATER: ITS CHEMISTRY AND PROPERTIES;
     IMPURITIES AND THEIR ACTION; TESTS OF PURITY           29

IV. WATER: ITS CHEMISTRY AND PROPERTIES; IMPURITIES AND
THEIR ACTION; TESTS OF PURITY--_continued_                  38

V. ACIDS AND ALKALIS                                        49

VI. BORIC ACID, BORAX, SOAP                                 57

VII. SHELLAC, WOOD SPIRIT, AND THE STIFFENING AND
     PROOFING PROCESS                                       62

VIII. MORDANTS: THEIR NATURE AND USE                        69

IX. DYESTUFFS AND COLOURS                                   79

X. DYESTUFFS AND COLORS--_continued_                        89

XI. DYEING OF WOOL AND FUR; AND OPTICAL PROPERTIES
    OF COLOURS                                             100

INDEX                                                      117



THE CHEMISTRY OF HAT MANUFACTURING



LECTURE I

TEXTILE FIBRES, PRINCIPALLY WOOL, FUR, AND HAIR


_Vegetable Fibres._--Textile fibres may be broadly distinguished as
vegetable and animal fibres. It is absolutely necessary, in order to
obtain a useful knowledge of the peculiarities and properties of animal
fibres generally, or even specially, that we should be, at least to some
extent, familiar with those of the vegetable fibres. I shall therefore
have, in the first place, something to tell you of certain principal
vegetable fibres before we commence the more special study of the animal
fibres most interesting to you as hat manufacturers, namely, wool, fur,
and hair. What cotton is as a vegetable product I shall not in detail
describe, but I will refer you to the interesting and complete work of
Dr. Bowman, _On the Structure of the Cotton Fibre_. Suffice it to say
that in certain plants and trees the seeds or fruit are surrounded, in
the pods in which they develop, with a downy substance, and that the
cotton shrub belongs to this class of plants. A fibre picked out from
the mass of the downy substance referred to, and examined under the
microscope, is found to be a spirally twisted band; or better, an
irregular, more or less flattened and twisted tube (see Fig. 1). We know
it is a tube, because on taking a thin, narrow slice across a fibre and
examining the slice under the microscope, we can see the hole or
perforation up the centre, forming the axis of the tube (see Fig. 2).
Mr. H. de Mosenthal, in an extremely interesting and valuable paper (see
_J.S.C.I._,[1] 1904, vol. xxiii. p. 292), has recently shown that the
cuticle of the cotton fibre is extremely porous, having, in addition to
pores, what appear to be minute stomata, the latter being frequently
arranged in oblique rows, as if they led into oblique lateral channels.
A cotton fibre varies from 2·5 to 6 centimetres in length, and in
breadth from 0·017 to 0·05 millimetre. The characteristics mentioned
make it very easy to distinguish cotton from other vegetable or animal
fibres. For example, another vegetable fibre is flax, or linen, and this
has a very different appearance under the microscope (_see_ Fig. 3). It
has a bamboo-like, or jointed appearance; its tubes are not flattened,
nor are they twisted. Flax belongs to a class called the bast fibres, a
name given to certain fibres obtained from the inner bark of different
plants. Jute also is a bast fibre. The finer qualities of it look like
flax, but, as we shall see, it is not chemically identical with cotton,
as linen or flax is. Another vegetable fibre, termed "cotton-silk," from
its beautiful, lustrous, silky appearance, has excited some attention,
because it grows freely in the German colony called the Camaroons, and
also on the Gold Coast. This fibre, under the microscope, differs
entirely in appearance from both cotton and flax fibres. Its fibres
resemble straight and thin, smooth, transparent, almost glassy tubes,
with large axial bores; in fact, if wetted in water you can see the
water and air bubbles in the tubes under the microscope. A more detailed
account of "cotton-silk" appears in a paper read by me before the
Society of Chemical Industry in 1886 (see _J.S.C.I._, 1886, vol. v. p.
642). Now the substance of the cotton, linen or flax, as well as that of
the cotton-silk fibres, is termed, chemically, cellulose. Raw cotton
consists of cellulose with about 5 per cent. of impurities. This
cellulose is a chemical compound of carbon, hydrogen, and oxygen, and,
according to the relative proportions of these constituents, it has had
the chemical formula C_{6}H_{10}O_{5} assigned to it. Each letter
stands for an atom of each constituent named, and the numerals tell us
the number of the constituent atoms in the whole compound atom of
cellulose. This cellulose is closely allied in composition to starch,
dextrin, and a form of sugar called glucose. It is possible to convert
cotton rags into this form of sugar--glucose--by treating first with
strong vitriol or sulphuric acid, and then boiling with dilute acid for
a long time. Before we leave these vegetable or cellulose fibres, I will
give you a means of testing them, so as to enable you to distinguish
them broadly from the animal fibres, amongst which are silk, wool, fur,
and hair. A good general test to distinguish a vegetable and an animal
fibre is the following, which is known as Molisch's test: To a very
small quantity, about 0·01 gram, of the well-washed cotton fibre, 1 c.c.
of water is added, then two to three drops of a 15 to 20 per cent.
solution of alpha-naphthol in alcohol, and finally an excess of
concentrated sulphuric acid; on agitating, a deep violet colour is
developed. By using thymol in place of the alpha-naphthol, a
red or scarlet colour is produced. If the fibre were one of an animal
nature, merely a yellow or greenish-yellow coloured solution would
result. I told you, however, that jute is not chemically identical with
cotton and linen. The substance of its fibre has been termed "bastose"
by Cross and Bevan, who have investigated it. It is not identical with
ordinary cellulose, for if we take a little of the jute, soak it in
dilute acid, then in chloride of lime or hypochlorite of soda, and
finally pass it through a bath of sulphite of soda, a beautiful crimson
colour develops upon it, not developed in the case of cellulose (cotton,
linen, etc.). It is certain that it is a kind of cellulose, but still
not identical with true cellulose. All animal fibres, when burnt, emit a
peculiar empyreumatic odour resembling that from burnt feathers, an
odour which no vegetable fibre under like circumstances emits. Hence a
good test is to burn a piece of the fibre in a lamp flame, and notice
the odour. All vegetable fibres are easily tendered, or rendered rotten,
by the action of even dilute mineral acids; with the additional action
of steam, the effect is much more rapid, as also if the fibre is allowed
to dry with the acid upon or in it. Animal fibres are not nearly so
sensitive under these conditions. But whereas caustic alkalis have not
much effect on vegetable fibres, if kept out of contact with the air,
the animal fibres are very quickly attacked. Superheated steam alone has
but little effect on cotton or vegetable fibres, but it would fuse or
melt wool. Based on these differences, methods have been devised and
patented for treating mixed woollen and cotton tissues--(1) with
hydrochloric acid gas, or moistening with dilute hydrochloric acid and
steaming, to remove all the cotton fibre; or (2) with a jet of
superheated steam, under a pressure of 5 atmospheres (75 lb. per square
inch), when the woollen fibre is simply melted out of the tissue, and
sinks to the bottom of the vessel, a vegetable tissue remaining
(Heddebault). If we write on paper with dilute sulphuric acid, and dry
and then heat the place written upon, the cellulose is destroyed and
charred, and we get black writing produced. The principle involved is
the same as in the separation of cotton from mixed woollen and cotton
goods by means of sulphuric acid or vitriol. The fabric containing
cotton, or let us say cellulose particles, is treated with dilute
vitriol, pressed or squeezed, and then roughly dried. That cellulose
then becomes mere dust, and is simply beaten out of the intact woollen
texture. The cellulose is, in a pure state, a white powder, of specific
gravity 1·5, _i.e._ one and a half times as heavy as water, and is quite
insoluble in such solvents as water, alcohol, ether; but it does
dissolve in a solution of hydrated oxide of copper in ammonia. On adding
acids to the cupric-ammonium solution, the cellulose is reprecipitated
in the form of a gelatinous mass. Cotton and linen are scarcely
dissolved at all by a solution of basic zinc chloride.

[Footnote 1: _J.S.C.I. = Journal of the Society of Chemical Industry._]

[Illustration: FIG. 1.]

[Illustration: FIG. 2.]

[Illustration: FIG. 3.]

[Illustration: FIG. 4.]

_Silk._--We now pass on to the animal fibres, and of these we must first
consider silk. This is one of the most perfect substances for use in the
textile arts. A silk fibre may be considered as a kind of rod of
solidified flexible gum, secreted in and exuded from glands placed on
the side of the body of the silk-worm. In Fig. 4 are shown the forms of
the silk fibre, in which there are no central cavities or axial bores as
in cotton and flax, and no signs of any cellular structure or external
markings, but a comparatively smooth, glassy surface. There is, however,
a longitudinal groove of more or less depth. The fibre is
semi-transparent, the beautiful pearly lustre being due to the
smoothness of the outer layer and its reflection of the light. In the
silk fibre there are two distinct parts: first, the central portion, or,
as we may regard it, the true fibre, chemically termed _fibroïn_; and
secondly, an envelope composed of a substance or substances, chemically
termed _sericin_, and often "silk-glue" or "silk-gum." Both the latter
and _fibroïn_ are composed of carbon, hydrogen, nitrogen, and oxygen.
Here there is thus one element more than in the vegetable fibres
previously referred to, namely, nitrogen; and this nitrogen is contained
in all the animal fibres. The outer envelope of silk-glue or sericin can
be dissolved off the inner fibroïn fibre by means of hot water, or warm
water with a little soap. Warm dilute (that is, weak) acids, such as
sulphuric acid, etc., also dissolve this silk-glue, and can be used like
soap solutions for ungumming silk. Dilute nitric acid only slightly
attacks silk, and colours it yellow; it would not so colour vegetable
fibres, and this forms a good test to distinguish silk from a vegetable
fibre. Cold strong acetic acid, so-called glacial acetic acid, removes
the yellowish colouring matter from raw silk without dissolving the
sericin or silk-gum. By heating under pressure with acetic acid,
however, silk is completely dissolved. Silk is also dissolved by strong
sulphuric acid, forming a brown thick liquid. If we add water to this
thick liquid, a clear solution is obtained, and then on adding tannic
acid the fibroïn is precipitated. Strong caustic potash or soda
dissolves silk; more easily if warm. Dilute caustic alkalis, if
sufficiently dilute, will dissolve off the sericin and leave the inner
fibre of fibroïn; but they are not so good for ungumming silk as soap
solutions are, as the fibre after treatment with them is deficient in
whiteness and brilliancy. Silk dissolves completely in hot basic zinc
chloride solution, and also in an alkaline solution of copper and
glycerin, which solutions do not dissolve vegetable fibres or wool.
Chlorine and bleaching-powder solutions soon attack and destroy silk,
and so another and milder agent, namely, sulphurous acid, is used to
bleach this fibre. Silk is easily dyed by the aniline and coal-tar
colours, and with beautiful effect, but it has little attraction for the
mineral colours.

_Wool_.--Next to silk as an animal fibre we come to wool and different
varieties of fur and hair covering certain classes of animals, such as
sheep, goats, rabbits, and hares. Generally, and without going at all
deeply into the subject, we may say that wool differs from fur and hair,
of which we may regard it as a variety, by being usually more elastic,
flexible, and curly, and because it possesses certain features of
surface structure which confer upon it the property of being more easily
matted together than fur and hair are. We must first shortly consider
the manner of growth of hair without spending too much time on this part
of the subject. The accompanying figure (see Fig. 5) shows a section of
the skin with a hair or wool fibre rooted in it. Here we may see that
the ground work, if we may so term it, is four-fold in structure.
Proceeding downwards, we have--(first) the outer skin, scarf-skin or
cuticle; (second) a second layer or skin called the _rete mucosum_,
forming the epidermis; (third) papillary layer; (fourth) the corium
layer, forming the dermis. The peculiar, globular, cellular masses below
in the corium are called adipose cells, and these throw off perspiration
or moisture, which is carried away to the surface by the glands shown
(called sudoriparous glands), which, as is seen, pass independently off
to the surface. Other glands terminate under the skin in the hair
follicles, which follicles or hair sockets contain or enclose the hair
roots. These glands terminating in the hair follicles secrete an oily
substance, which bathes and lubricates as well as nourishes the hair.
With respect to the origin of the hair or wool fibre, this is formed
inside the follicle by the exuding therefrom of a plastic liquid or
lymph; this latter gradually becomes granular, and is then formed into
cells, which, as the growth proceeds, are elongated into fibres, which
form the central portion of the hair. Just as with the trunk of a tree,
we have an outer dense portion, the bark, an inner less dense and more
cellular layer, and an inmost portion which is most cellular and
porous; so with a hair, the central portion is loose and porous, the
outer more and more dense. On glancing at the figure (Fig. 6) of the
longitudinal section of a human hair, we see first the outer portion,
like the bark of a tree, consisting of a dense sheath of flattened
scales, then comes an inner lining of closely-packed fibrous cells, and
frequently an inner well-marked central bundle of larger and rounder
cells, forming a medullary axis. The transverse section (Fig. 7) shows
this exceedingly well. The end of a hair is generally pointed, sometimes
filamentous. The lower extremity is larger than the shaft, and
terminates in a conical bulb, or mass of cells, which forms the root of
the hair. In the next figure (Fig. 8) we are supposed to have separated
these cells, and above, (a), we see some of the cells from the central
pith or medulla, and fat globules; between, (b), some of the
intermediate elongated or angular cells; and below, (c), two flattened,
compressed, structureless, and horny scales from the outer portion of
the hair. Now these latter flattened scales are of great importance.
Their character and mode of connection with the stratum, or cortical
substance, below, not only make all the difference between wool and
hair, but also determine the extent and degree of that peculiar property
of interlocking of the hairs known as felting. Let us now again look at
a human hair. The light was reflected from this hair as it lay under the
microscope, and now we see the reason of the saw-like edge in the
longitudinal section, for just as the tiles lie on the roof of a house,
or the scales on the back of a fish, so the whole surface of the hair
is externally coated with a firmly adhering layer of flat overlying
scales, with not very even upper edges, as you see. The upper or free
edges of these scales are all directed towards the end of the hair, and
away from the root. But when you look at a hair in its natural state you
cannot see these scales, so flat do they lie on the hair-shaft. What you
see are only irregular transverse lines across it. Now I come to a
matter of great importance, as will later on appear in connection with
means for promoting felting properties. If a hair such as described,
with the scales lying flat on the shaft, be treated with certain
substances or reagents which act upon and dissolve, or decompose or
disintegrate its parts, then the free edges of these scales rise up,
they "set their backs up," so to say. They, in fact, stand off like the
scales of a fir-cone, and at length act like the fir-cone in ripening,
at last becoming entirely loose. As regards wool and fur, these scales
are of the utmost importance, for very marked differences exist even in
the wool of a single sheep, or the fur of a single hare. It is the duty
of the wool-sorter to distinguish and separate the various qualities in
each fleece, and of the furrier to do the same in the case of each fur.
In short, upon the nature and arrangement and conformation of the scales
on the hair-shafts, especially as regards those free upper edges,
depends the distinction of the value of many classes of wool and fur.
These scales vary both as to nature and arrangement in the case of the
hairs of different animals, so that by the aid of the microscope we have
often a means of determining from what kind of animal the hair has been
derived. It is on the nature of this outside scaly covering of the
shaft, and in the manner of attachment of these scaly plates, that the
true distinction between wool and hair rests. The principal epidermal
characteristic of a true wool is the capacity of its fibres to felt or
mat together. This arises from the greater looseness of the scaly
covering of the hair, so that when opposing hairs come into contact, the
scales interlock (see Fig. 9), and thus the fibres are held together.
Just as with hair, the scales of which have their free edges pointing
upwards away from the root, and towards the extremity of the hair, so
with wool. When the wool is on the back of the sheep, the scales of the
woolly hair all point in the same direction, so that while maintained in
that attitude the individual hairs slide over one another, and do not
tend to felt or mat; if they did, woe betide the animal. The fact of the
peculiar serrated, scaly structure of hair and wool is easily proved by
working a hair between the fingers. If, for instance, a human hair be
placed between finger and thumb, and gently rubbed by the alternate
motion of finger and thumb together, it will then invariably move in the
direction of the root, quite independently of the will of the person
performing the test. A glance at the form of the typical wool fibres
shown (see Fig. 10), will show the considerable difference between a
wool and a hair fibre. You will observe that the scales of the wool
fibre are rather pointed than rounded at their free edges, and that at
intervals we have a kind of composite and jagged-edged funnels, fitting
into each other, and thus making up the covering of the cylindrical
portion of the fibre. The sharpened, jagged edges enable these scales
more easily to get under the opposing scales, and to penetrate inwards
and downwards according to the pressure exerted. The free edges of the
scales of wool are much longer and deeper than in the case of hair. In
hair the overlapping scales are attached to the under layer up to the
edges of those scales, and at this extremity can only be detached by
the use of certain reagents. But this is not so with wool, for here the
ends of the scales are, for nearly two-thirds of their length, free, and
are, moreover, partially turned outwards. One of the fibres shown in
Fig. 10 is that of the merino sheep, and is one of the most valuable and
beautiful wools grown. There you have the type of a fibre best suited
for textile purposes, and the more closely different hairs approach
this, the more suitable and valuable they become for those purposes, and
_vice versâ_. With regard to the curly structure of wool, which
increases the matting tendency, though the true cause of this curl is
not known, there appears to be a close relationship between the tendency
to curl, the fineness of the fibre, and the number of scales per linear
inch upon the surface. With regard to hair and fur, I have already shown
that serrated fibres are not specially peculiar to sheep, but are much
more widely diffused. Most of the higher members of the mammalia family
possess a hairy covering of some sort, and in by far the larger number
is found a tendency to produce an undergrowth of fine woolly fibre,
especially in the winter time. The differences of human hair and hairs
generally, from the higher to the lower forms of mammalia, consist only
in variations of size and arrangement as regards the cells composing the
different parts of the fibre, as well as in a greater or less
development of the scales on the covering or external hair surface.
Thus, under the microscope, the wool and hairs of various animals, as
also even hairs from different parts of the same animal, show a great
variety of structure, development, and appearance.

[Illustration: FIG. 5.]

[Illustration: FIG. 6.]

[Illustration: FIG. 7.]

[Illustration: FIG. 8.]

[Illustration: FIG. 9.]

[Illustration:

    Finest merino wool fibre.
    Typical wool fibre.
    Fibre of wool from Chinese sheep.

FIG. 10.]

[Illustration: FIG. 11.]

[Illustration: FIG. 12.]

We have already observed that hair, if needed for felting, is all the
better--provided, of course, no injury is done to the fibre itself--for
some treatment, by which the scales otherwise lying flatter on the
hair-shafts than in the case of the hairs of wool, are made to stand up
somewhat, extending outwards their free edges. This brings me to the
consideration of a practice pursued by furriers for this purpose, and
known as the _sécretage_ or "carrotting" process; it consists in a
treatment with a solution of mercuric nitrate in nitric acid, in order
to improve the felting qualities of the fur. This acid mixture is
brushed on to the fur, which is cut from the skin by a suitable sharp
cutting or shearing machine. A Manchester furrier, who gave me specimens
of some fur untreated by the process, and also some of the same fur that
had been treated, informed me that others of his line of business use
more mercury than he does, _i.e._ leave less free nitric acid in their
mixture; but he prefers his own method, and thinks it answers best for
the promotion of felting. The treated fur he gave me was turned yellow
with the nitric acid, in parts brown, and here and there the hairs were
slightly matted with the acid. In my opinion the fur must suffer from
such unequal treatment with such strong acid, and in the final process
of finishing I should not be surprised if difficulty were found in
getting a high degree of lustre and finish upon hairs thus roughened or
partially disintegrated. Figs. 11 and 12 respectively illustrate fur
fibres from different parts of the same hare before and after the
treatment. In examining one of these fibres from the side of a hare, you
see what the cause of this roughness is, and what is also the cause of
the difficulty in giving a polish or finish. The free edges are
partially disintegrated, etched as it were, besides being caused to
stand out. A weaker acid ought to be used, or more mercury and less
acid. As we shall afterwards see, another dangerous agent, if not
carefully used, is bichrome (bichromate of potassium), which is also
liable to roughen and injure the fibre, and thus interfere with the
final production of a good finish.



LECTURE II

TEXTILE FIBRES, PRINCIPALLY WOOL, FUR, AND HAIR--_Continued_


With regard to the preparation of fur by acid mixtures for felting,
mentioned in the last lecture, I will tell you what I think I should
recommend. In all wool and fur there is a certain amount of grease, and
this may vary in different parts of the material. Where there is most,
however, the acid, nitric acid, or nitric acid solution of nitrate of
mercury, will wet, and so act on the fur, least. But the action ought to
be uniform, and I feel sure it cannot be until the grease is removed. I
should therefore first wash the felts on the fur side with a weak
alkaline solution, one of carbonate of soda, free from any caustic, to
remove all grease, then with water to remove alkali; and my belief is
that a weaker and less acid solution of nitric acid and nitrate of
mercury, and a smaller quantity of it, would then do the work required,
and do it more uniformly.

A question frequently asked is: "Why will dead wool not felt?" Answer:
If the animal become weak and diseased, the wool suffers degradation;
also, with improvement in health follows _pari passu_, improvement in
the wool structure, which means increase both in number and vigour of
the scales on the wool fibres, increase of the serrated ends of these,
and of their regularity. In weakness and disease the number of scales in
a given hair-shaft diminishes, and these become finer and less
pronounced. The fibres themselves also become attenuated. Hence when
disease becomes death, we have considerably degraded fibres. This is
seen clearly in the subjoined figures (see Fig. 13), which are of wool
fibres from animals that have died of disease. The fibres are attenuated
and irregular, the scale markings and edges have almost disappeared in
some places, and are generally scanty and meagre in development. It is
no wonder that such "dead wool" will be badly adapted for felting. "Dead
wool" is nearly as bad as "kempy" wool, in which malformation of fibre
has occurred. In such "kemps," as Dr. Bowman has shown, scales have
disappeared, and the fibre has become, in part or whole, a dense,
non-cellular structure, resisting dye-penetration and felting (see Fig.
14).

[Illustration: FIG. 13.]

[Illustration: FIG. 14.]

One of the physical properties of wool is its hygroscopicity or power of
absorbing moisture. As the very structure of wool and fur fibre would
lead us to suppose, these substances are able to absorb a very
considerable amount of water without appearing damp. If exposed freely
to the air in warm and dry weather, wool retains from 8 to 10 per cent.,
and if in a damp place for some time, it may absorb as much as from 30
to 50 per cent. of water: Wool, fur, or hair that has been washed,
absorbs the most moisture; indeed, the amount of water taken up varies
inversely with the fatty or oily matter present. Hence the less fat the
more moisture. In the washed wool, those fibres in which the cells are
more loosely arranged have the greatest absorbing power for water. No
doubt the moisture finds its way in between the cells of the wool fibre
from which the oil or fat has been removed. But I need hardly remind you
that if wool and fur are capable, according to the circumstances under
which they are placed, of absorbing so much moisture as that indicated,
it becomes (especially in times of pressure and competition) very
important to inquire if it be not worth while to cease paying wool and
fur prices for mere water. This question was answered long ago in the
negative by our Continental neighbours, and in Germany, France, and
Switzerland official conditioning establishments have been founded by
the Governments of those countries for the purpose of testing lots of
purchased wool and silk, etc., for moisture, in order that this moisture
may be deducted from the invoices, and cash paid for real dry wool, etc.
I would point out that if you, as hat manufacturers, desire to enter the
lists with Germany, you must not let her have any advantage you have
not, and it is an advantage to pay for what you know exactly the
composition of, rather than for an article that may contain 7 per cent.
or, for aught you know, 17 per cent. or 30 per cent. of water. There is,
so far as I know, no testing for water in wools and furs in this
country, and certainly no "conditioning establishments" (1887), and, I
suppose, if a German or French wool merchant or furrier could be
imagined as selling wool, etc., in part to a German or French firm, and
in part to an English one, the latter would take the material without a
murmur, though it might contain 10 per cent., or, peradventure, 30 per
cent. of water, and no doubt the foreign, just as the English merchant
or dealer, would get the best price he could, and regard the possible 10
per cent. or 30 per cent. of water present with certainly the more
equanimity the more of that very cheap element there were present. But
look at the other side. The German or French firm samples its lot as
delivered, takes the sample to be tested, and that 10 or 30 per cent. of
water is deducted, and only the dry wool is paid for. A few little
mistakes of this kind, I need hardly say, will altogether form a kind of
_vade mecum_ for the foreign competitor.

We will now see what the effect of water is in the felting operation.
Especially hot water assists that operation, and the effect is a
curious one. When acid is added as well, the felting is still further
increased, and shrinking also takes place. As already shown you, the
free ends of the scales, themselves softened by the warm dilute acid,
are extended and project more, and stand out from the shafts of the
hairs. On the whole, were I a hat manufacturer, I should prefer to buy
my fur untreated by that nitric acid and mercury process previously
referred to, and promote its felting properties myself by the less
severe and more rational course of proceeding, such, for example, as
treatment with warm dilute acid. We have referred to two enemies
standing in the way to the obtainment of a final lustre and finish on
felted wool or fur, now let us expose a third. In the black dyeing of
the hat-forms a boiling process is used. Let us hear what Dr. Bowman, in
his work on the wool fibre, says with regard to boiling with water.
"Wool which looked quite bright when well washed with tepid water, was
decidedly duller when kept for some time in water at a temperature of
160° F., and the same wool, when subjected to boiling water at 212° F.,
became quite dull and lustreless. When tested for strength, the same
fibres which carried on the average 500 grains without breaking before
boiling, after boiling would not bear more than 480 grains." Hence this
third enemy is a boiling process, especially a long-continued one if
only with water itself. If we could use coal-tar colours and dye in only
a warm weak acid bath, not boil, we could get better lustre and finish.

We will now turn our attention to the chemical composition of wool and
fur fibres. On chemical analysis still another element is found over and
above those mentioned as the constituents of silk fibre. In silk, you
will recollect, we observed the presence of carbon, hydrogen, oxygen,
and nitrogen. In wool, fur, etc., we must add a fifth constituent,
namely, sulphur. Here is an analysis of pure German wool--Carbon, 49·25
per cent.; hydrogen, 7·57; oxygen, 23·66; nitrogen, 15·86; sulphur,
3·66--total, 100·00. If you heat either wool, fur, or hair to 130° C.,
it begins to decompose, and to give off ammonia; if still further heated
to from 140° to 150° C., vapours containing sulphur are evolved. If some
wool be placed in a dry glass tube, and heated strongly so as to cause
destructive distillation, products containing much carbonate of ammonium
are given off. The ammonia is easily detected by its smell of hartshorn
and the blue colour produced on a piece of reddened litmus paper, the
latter being a general test to distinguish alkalis, like ammonia, soda,
and potash, from acids. No vegetable fibres will, under any
circumstances, give off ammonia. It may be asked, "But what does the
production of ammonia prove?" I reply, the "backbone," chemically
speaking, of ammonia is nitrogen. Ammonia is a compound of nitrogen and
hydrogen, and is formulated NH_{3}, and hence to discover ammonia in the
products as mentioned is to prove the prior existence of its nitrogen in
the wool, fur, and hair fibres.

_Action of Acids on Wool, etc._--Dilute solutions of vitriol (sulphuric
acid) or hydrochloric acid (muriatic acid, spirits of salt) have little
effect on wool, whether warm or cold, except to open out the scales and
confer roughness on the fibre. Used in the concentrated state, however,
the wool or fur would soon be disintegrated and ruined. But under all
circumstances the action is far less than on cotton, which is destroyed
at once and completely. Nitric acid acts like sulphuric and hydrochloric
acids, but it gives a yellow colour to the fibre. You see this clearly
enough in the fur that comes from your furriers after the treatment they
subject it to with nitric acid and nitrate of mercury. There is a
process known called the stripping of wool, and it consists in
destroying the colour of wool and woollen goods already dyed, in order
that they may be re-dyed. Listen, however, to the important precautions
followed: A nitric acid not stronger than from 3° to 4° Twaddell is
used, and care is taken not to prolong the action more than three or
four minutes.

_Action of Alkalis._--Alkalis have a very considerable action on fur and
wool, but the effects vary a good deal according to the kind of alkali
used, the strength and the temperature of the solution, as also, of
course, the length of period of contact. The caustic alkalis, potash and
soda, under all conditions affect wool and fur injuriously. In fact, we
have a method of recovering indigo from indigo-dyed woollen rags, based
on the solubility of the wool in hot caustic soda. The wool dissolves,
and the indigo, being insoluble, remains, and can be recovered. Alkaline
carbonates and soap in solution have little or no injurious action if
not too strong, and if the temperature be not over 50° C. (106° F.).
Soap and carbonate of ammonium have the least injurious action. Every
washer or scourer of wool, when he uses soaps, should first ascertain if
they are free from excess of alkali, _i.e._ that they contain no free
alkali; and when he uses soda ash (sodium carbonate), that it contains
no caustic alkali. Lime, in water or otherwise, acts injuriously,
rendering the fibre brittle.

_Reactions and tests proving chemical differences and illustrating modes
of discriminating and separating vegetable fibres, silk and wool, fur,
etc._--You will remember I stated that the vegetable fibre differs
chemically from those of silk, and silk from wool, fur, and hair, in
that with the first we have as constituents only carbon, hydrogen, and
oxygen; in silk we have carbon, hydrogen, oxygen, and nitrogen; whilst
in wool, fur, and hair we have carbon, hydrogen, oxygen, nitrogen, and
sulphur. I have already shown you that if we can liberate by any means
ammonia from a substance, we have practically proved the presence of
nitrogen in that substance, for ammonia is a nitrogen compound. As
regards sulphur and its compounds, that ill-smelling gas, sulphuretted
hydrogen, which occurs in rotten eggs, in organic effluvia from
cesspools and the like, and which in the case of bad eggs, and to some
extent with good eggs, turns the silver spoons black, and in the case of
white lead paints turns these brown or black, I can show you some still
more convincing proofs that sulphur is contained in wool, fur, and hair,
and not in silk nor in vegetable fibres. First, I will heat strongly
some cotton with a little soda-lime in a tube, and hold a piece of
moistened red litmus paper over the mouth of the tube. If nitrogen is
present it will take up hydrogen in the decomposition ensuing, and
escape as ammonia, which will turn the red litmus paper blue. With the
cotton, however, no ammonia escapes, no turning of the piece of red
litmus paper blue is observed, and so no nitrogen can be present in the
cotton fibre. Secondly, I will similarly treat some silk. Ammonia
escapes, turns the red litmus paper blue, possesses the smell like
hartshorn, and produces, with hydrochloric acid on the stopper of a
bottle, dense white fumes of sal-ammoniac (ammonium chloride). Hence
silk contains nitrogen. Thirdly, I will heat some fur with soda-lime.
Ammonia escapes, giving all the reactions described under silk. Hence
fur, wool, etc., contain nitrogen. As regards proofs of all three of
these classes of fibres containing carbon, hydrogen, and oxygen, the
char they all leave behind on heating in a closed vessel is the carbon
itself present. For the hydrogen and oxygen, a perfectly dry sample of
any of these fabrics is taken, of course in quantity, and heated
strongly in a closed vessel furnished with a condensing worm like a
still. You will find all give you water as a condensate--the vegetable
fibre, acid water; the animal fibres, alkaline water from the ammonia.
The presence of water proves both hydrogen and oxygen, since water is a
compound of these elements. If you put a piece of potassium in contact
with the water, the latter will at once decompose, the potassium
absorbing the oxygen, and setting free the hydrogen as gas, which you
could collect and ignite with a match, when you would find it would
burn. That hydrogen was the hydrogen forming part of your cotton, silk,
or wool, as the case might be. We must now attack the question of
sulphur. First, we prepare a little alkaline lead solution (sodium
plumbate) by adding caustic soda to a solution of lead acetate or sugar
of lead, until the white precipitate first formed is just dissolved.
That is one of our reagents; the other is a solution of a red-coloured
salt called nitroprusside of sodium, made by the action of nitric acid
on sodium ferrocyanide (yellow prussiate). The first-named is very
sensitive to sulphur, and turns black directly. To show this, we take a
quantity of flowers of sulphur, dissolve in caustic soda, and add to the
lead solution. It turns black at once, because the sulphur unites with
the lead to form black sulphide of lead. The nitroprusside, however,
gives a beautiful crimson-purple coloration. Now on taking a little
cotton and heating with the caustic alkaline lead solution, if sulphur
were present in that cotton, the fibre would turn black or brown, for
the lead would at once absorb such sulphur, and form in the fibre soaked
with it, black sulphide of lead. No such coloration is formed, so cotton
does not contain sulphur. Secondly, we must test silk. Silk contains
nitrogen, like wool, but does it contain sulphur? The answer furnished
by our tests is--no! since the fibre is not coloured brown or black on
heating with the alkaline lead solution. Thirdly, we try some white
Berlin wool, so that we can easily see the change of colour if it takes
place. In the hot lead solution the wool turns black, lead sulphide
being formed. On adding the nitroprusside solution to a fresh portion of
wool boiled with caustic soda, to dissolve out the sulphur, a splendid
purple coloration is produced. Fur and hair would, of course, do the
same thing. Lead solutions have been used for dyeing the hair black; not
caustic alkaline solutions like this, however. They would do something
more than turn the hair black--probably give rise to some vigorous
exercise of muscular power! Still it has been found that even the lead
solutions employed have, through gradual absorption into the system,
whilst dyeing the hair black, also caused colics and contractions of the
limbs.

Having now found means for proving the presence of the various elements
composing cotton, silk, and wool, fur or hair, we come to methods that
have been proposed for distinguishing these fibres more generally, and
for quantitatively determining them in mixtures. One of the best of the
reagents for this purpose is the basic zinc chloride already referred
to. This is made as follows: 100 parts of fused zinc chloride, 85 parts
of water, and 4 parts of zinc oxide are boiled together until a clear
solution is obtained. This solution dissolves silk slowly in the cold,
quickly if hot, and forms a thick gummy liquid. Wool, fur, and vegetable
fibres are not affected by it. Hence if we had a mixture, and treated
with this solution, we could strain off the liquid containing the
dissolved silk, and would get cotton and wool left. On weighing before
and after such treatment, the difference in weights would give us the
silk present. The residue boiled with caustic soda would lose all its
wool, which is soluble in hot strong caustic alkali. Again straining
off, we should get only the cotton or other vegetable fibre left, and
thus our problem would be solved. Of course there are certain additional
niceties and modifications still needed, and I must refer you for the
method in full to the _Journal of the Society of Chemical Industry_,
1882, page 64; also 1884, page 517. I will now conclude with some tests
with alkaline and acid reagents, taken in order, and first the acids.
These will also impress upon our minds the effects of acids and alkalis
on the different kinds of fibres.

I. In three flasks three similar portions of cotton lamp-wick, woollen
yarn, and silk are placed, after previously moistening them in water and
wringing them out. To each is now added similar quantities of
concentrated sulphuric acid. The cotton is quickly broken up and
dissolved, especially if assisted by gentle warming, and at last a
brown, probably a black-brown, solution is obtained. The woollen is a
little broken up, but not much to the naked eye, and the vitriol is not
coloured. The silk is at once dissolved, even in the cold acid. We now
add excess of water to the contents of each flask. A brownish, though
clear, solution is produced in the case of cotton; the woollen floats
not much injured in the acid, whilst a clear limpid solution is obtained
with the silk. On adding tannic acid solution to all three, only the
silk yields a precipitate, a rather curdy one consisting of fibroïn.

II. Three specimens of cotton, wool, and silk, respectively, are touched
with nitric acid. Cotton is not coloured, but wool and silk are stained
yellow; they are practically dyed.

III. Three specimens, of cotton, wool, and silk, respectively, are
placed in three flasks, and caustic soda solution of specific gravity
1·05 (10° Twaddell) is added. On boiling, the wool and silk dissolve,
whilst the cellulose fibre, cotton, remains undestroyed.

IV. If, instead of caustic soda as in III., a solution of oxide of
copper in ammonia be used, cotton and silk are dissolved, but wool
remains unchanged, _i.e._ undissolved. If sugar or gum solutions be
added to the solutions of cotton and silk, the cotton cellulose is
precipitated, whilst the silk is not, but remains in solution.

V. Another alkaline solvent for silk, which, however, leaves undissolved
cotton and wool, is prepared as follows: 16 grains of copper sulphate
("blue vitriol," "bluestone") are dissolved in 150 c.c. of water, and
then 16 grains of glycerin are added. To this mixture a solution of
caustic soda is added until the precipitate first formed is just
re-dissolved, so as not to leave an excess of caustic soda present.



LECTURE III

WATER: ITS CHEMISTRY AND PROPERTIES; IMPURITIES AND THEIR ACTION; TESTS
OF PURITY


I have already had occasion to refer, in my last Lecture, to water as a
chemical substance, as a compound containing and consisting of hydrogen
and oxygen. What are these water constituents, hydrogen and oxygen? Each
of them is a gas, but each a gas having totally different properties. On
decomposing water and collecting the one of these two gases, the
hydrogen gas, in one vessel, and the other, the oxygen gas, in another
vessel, twice as large a volume of hydrogen gas is given off by the
decomposing water as of oxygen. You may now notice a certain meaning in
the formula assigned to water, H_{2}O: two volumes of hydrogen combined
with one of oxygen; and it may be added that when such combination takes
place, not three volumes of resulting water vapour (steam), but two
volumes are produced. This combination of the two gases, when mixed
together, is determined by heating to a high temperature, or by passing
an electric spark; it then takes place with the consequent sudden
condensation of three volumes of mixture to two of compound, so as to
cause an explosion. I may also mention that as regards the weights of
these bodies, oxygen and hydrogen, the first is sixteen times as heavy
as the second; and since we adopt hydrogen as the unit, we may consider
H to stand for hydrogen, and also to signify 1--the unit; whilst O
means oxygen, and also 16. Hence the compound atom or molecule of
water, H_{2}O, weighs 18. I must now show you that these two gases are
possessed of totally different properties. Some gases will extinguish a
flame; some will cause the flame to burn brilliantly, but will not burn
themselves; and some will take fire and burn themselves, though
extinguishing the flame which has ignited them. We say the first are
non-combustible, and will not support combustion; the second are
supporters of combustion, the third are combustible gases. Of course
these are, as the lawyers say, only _ex parte_ statements of the truth;
still they are usually accepted. Oxygen gas will ignite a red-hot match,
but hydrogen will extinguish an inflamed one, though it will itself
burn. You generally think of water as the great antithesis of, the
universal antidote for, fire. The truth is here again only of an _ex
parte_ character, as I will show you. If I can, by means of a substance
having a more intense affinity for oxygen than hydrogen has, rob water
of its oxygen, I necessarily set the hydrogen that was combined with
that oxygen free. If the heat caused by the chemical struggle, so to
say, is great, that hydrogen will be inflamed and burn. Thus we are
destroying that antithesis, we are causing the water to yield us fire. I
will do this by putting potassium on water, and even in the cold this
potassium will seize upon the oxygen of the water, and the hydrogen will
take fire.

_Specific Gravity._--We must now hasten to other considerations of
importance. Water is generally taken as the unit in specific gravities
assigned to liquids and solids. This simply means that when we desire to
express how heavy a thing is, we are compelled to say it is so many
times heavier or lighter than something. That something is generally
water, which is regarded, consequently, as unit or figure 1. A body of
specific gravity 1·5, or 1-1/2, means that that body is 1-1/2 or 1·5
times as heavy as water. As hat manufacturers, you will have mostly to
do with the specific gravities of liquids, aqueous solutions, and you
will hear more of Twaddell degrees. The Twaddell hydrometer, or
instrument for measuring the specific gravities of liquids, is so
constructed that when it stands in water, the water is just level with
its zero or 0° mark. Well, since in your reading of methods and new
processes, you will often meet with specific gravity numbers and desire
to convert these into Twaddell degrees, I will give you a simple means
of doing this. Add cyphers so as to make into a number of four figures,
then strike out the unit and decimal point farthest to the left, and
divide the residue by 5, and you get the corresponding Twaddell degrees.
If you have Twaddell degrees, simply multiply by 5, and add 1000 to the
result, and you get the specific gravity as usually taken, with water as
the unit, or in this case as 1000. An instrument much used on the
Continent is the Beaumé hydrometer. The degrees (_n_) indicated by this
instrument can be converted into specific gravity (_d_) by the

    formula: _d_ = 144·3/(144·3 - n)

_Ebullition or Boiling of Water, Steam._--The atmosphere around us is
composed of a mixture of nitrogen and oxygen gases; not a compound of
these gases, as water is of hydrogen and oxygen, but a mixture more like
sand and water or smoke and air. This mass of gases has weight, and
presses upon objects at the surface of the earth to the extent of 15 lb.
on the square inch. Now some liquids, such as water, were it not for
this atmospheric pressure, would not remain liquids at all, but would
become gases. The pressure thus tends to squeeze gases together and
convert them into liquids. Any force that causes gases to contract will
do the same thing, of course--for example, cold; and _ceteris paribus_
removal of pressure and expansion by heat will act so as to gasify
liquids. When in the expansion of liquids a certain stage or degree is
reached, different for different liquids, gas begins to escape so
quickly from the liquid that bubbles of vapour are continually formed
and escape. This is called ebullition or boiling. A certain removal of
pressure, or expansion by heat, is necessary to produce this, _i.e._ to
reach the boiling-point of the liquid. As regards the heat necessary for
the boiling of water at the surface of the earth, _i.e._ under the
atmospheric pressure of 15 lb. on the square inch, this is shown on the
thermometer of Fahrenheit as 212°, and on the simpler centigrade one, as
100°, water freezing at 0° C. But if what I have said is true, when we
remove some of the atmospheric pressure, the water should boil with a
less heat than will cause the mercury in the thermometer to rise to 100°
C., and if we take off all the pressure, the water ought to boil and
freeze at the same time. This actually happens in the Carré ice-making
machine. The question now arises, "Why does the water freeze in the
Carré machine?" All substances require certain amounts of heat to enable
them to take and to maintain the liquid state if they are ordinarily
solid, and the gaseous state if ordinarily liquid or solid, and the
greater the change of state the greater the heat needed. Moreover, this
heat does not make them warm, it is simply absorbed or swallowed up, and
becomes latent, and is merely necessary to maintain the new condition
assumed. In the case of the Carré machine, liquid water is, by removal
of the atmospheric pressure, coerced, as it were, to take the gaseous
form. But to do so it needs to absorb the requisite amount of heat to
aid it in taking that form, and this heat it must take up from all
surrounding warm objects. It absorbs quickly all it can get out of
itself as liquid water, out of the glass vessel containing it, and from
the surrounding air. But the process of gasification with ebullition
goes on so quickly that the temperature of the water thus robbed of heat
quickly falls to 0° C., and the remaining water freezes. Thus, then, by
pumping out the air from a vessel, _i.e._ working in a vacuum, we can
boil a liquid in such exhausted vessel far below its ordinary boiling
temperature in the open air. This fact is of the utmost industrial
importance. But touching this question of latent heat, you may ask me
for my proof that there is latent heat, and a large amount of it, in a
substance that feels perfectly cold. I have told you that a gasified
liquid, or a liquefied solid, or most of all a gasified solid, contains
such heat, and if reconverted into liquid and solid forms respectively,
that heat is evolved, or becomes sensible heat, and then it can be
decidedly felt and indicated by the thermometer. Take the case of a
liquid suddenly solidifying. The heat latent in that liquid, and
necessary to keep it a liquid, is no longer necessary and comes out, and
the substance appears to become hot. Quicklime is a cold, white, solid
substance, but there is a compound of water and lime--slaked lime--which
is also a solid powdery substance, called by the chemist, hydrate of
lime. The water used to slake the quicklime is a liquid, and it may be
ice-cold water, but to form hydrate of lime it must assume a solid form,
and hence can and does dispense with its heat of liquefaction in the
change of state. You all know how hot lime becomes on slaking with
water. Of course we have heat of chemical combination here as well as
evolution of latent heat. As another example, we may take a solution of
acetate of soda, so strong that it is just on the point of
crystallising. If it crystallises it solidifies, and the liquid
consequently gives up its latent heat of liquefaction. We will make it
crystallise, first connecting the tube containing it to another one
containing a coloured liquid and closed by a cork carrying a narrow tube
dipping into the coloured liquid. On crystallising, the solution gives
off heat, as is shown by the expansion of the air in the corked tube,
and the consequent forcing of the coloured liquid up the narrow tube.
Consequently in your works you never dissolve a salt or crystal in water
or other liquid without rendering heat latent, or consuming heat; you
never allow steam to condense in the steam pipes about the premises
without losing vastly more heat than possibly many are aware of. Let us
inquire as to the latent heat of water and of steam.

_Latent Heats of Water and Steam._--If we mix 1 kilogram (about 2 lb.)
of ice (of course at zero or 0° C.) with 1 kilogram of water at 79° C.,
and stir well till the ice is melted, _i.e._ has changed its state from
solid to liquid, we find, on putting a thermometer in, the temperature
is only 0° C. This simply means that 79° of heat (centigrade degrees)
have become latent, and represent the heat of liquefaction of 1 kilogram
of ice. Had we mixed 1 kilogram of water at 0° C. with 1 kilogram of
water at 79° C. there would have been no change of state, and the
temperature of the mixture might be represented as a distribution of the
79° C. through the whole mass of the 2 kilograms, and so would be
39-1/2° C. We say, therefore, the latent heat of water is the heat which
is absorbed or rendered latent when a unit of weight, say 1 kilogram of
water as ice, melts and liquefies to a unit of water at zero, or it is
79 heat units. These 79 units of heat would raise 79 units of weight of
liquid water through 1° C., or one unit of liquid water through 79°.

Let us now inquire what the latent heat of steam is. If we take 1
kilogram of water at 0° C. and blow steam from boiling water at 100° C.
into it until the water just boils, and then stop and weigh the
resulting water, we shall find it amounts to 1·187 kilograms, so that
0·187 kilogram of water which was in the gaseous steam form, and had
besides a sensible heat of 100° C., has changed its state to that of
liquid water. This liquid water, being at the boiling-point, has still
the 100° C. of sensible heat, and hence the water in the gaseous steam
form can have given up to the water at 0° C. into which it was blown,
only the latent heat of gasification which was not sensible, but by
virtue of which it was enabled to assume the gaseous form. But if 0·187
kilogram of steam at 100° C. can heat 1 kilogram of water through 100
degrees, then 1 kilogram of steam can raise 5·36 kilograms of ice-cold
water through 100 degrees, or 536 kilograms through 1 degree, and thus
the latent heat of steam is 536 heat units.

_Effect of Increase of Pressure on the Boiling of Water._--Now we have
referred to diminution of pressure and its effect on the boiling-point
of water, and I may point out that by increasing the pressure, such,
_e.g._, as boiling water under a high pressure of steam, you raise the
boiling-point. There are some industrial operations in which the action
of certain boiling solutions is unavailing to effect certain
decompositions or other ends when the boiling is carried on under the
ordinary atmospheric pressure, and boiling in closed and strong vessels
under pressure must be resorted to. Take as an example the wood-pulp
process for making paper from wood shavings. Boiling in open pans with
caustic soda lye is insufficient to reduce the wood to pulp, and so
boiling in strong vessels under pressure is adopted. The temperature of
the solution rises far above 212° F. (100° C.). Let us see what may
result chemically from the attainment of such high temperatures of water
in our steam boilers working under high pressures. If you blow ordinary
steam at 212° F. or 100° C., into fats or oils, the fats and oils remain
undecomposed; but suppose you let fatty and oily matters of animal or
vegetable origin, such as lubricants, get into your boiler feed-water
and so into your boiler, what will happen? I have only to tell you that
a process is patented for decomposing fats with superheated steam, to
drive or distil over the admixed fatty acids and glycerin, in order to
show you that in your boilers such greasy matters will be more or less
decomposed. Fats are neutral as fats, and will not injure the iron of
the boilers; but once decompose them and they are split up into an acid
called a fat acid, and glycerin. That fat acid at the high temperature
soon attacks your boilers and pipes, and eats away the iron. That is one
of the curious results that may follow at such high temperatures.
Mineral or hydrocarbon oils do not contain these fat acids, and so
cannot possibly, even with high-pressure steam, corrode the boiler
metal.

_Effect of Dissolved Salts on the Boiling of Water._--Let us inquire
what this effect is? Suppose we dissolve a quantity of a salt in water,
and then blow steam at 100° C. (212° F.) into that water, the latter
will boil not at 212° F., but at a higher temperature. There is a
certain industrial process I know of, in course of which it is necessary
first to maintain a vessel containing water, by means of a heated closed
steam coil, at 212° F. (100° C.), and at a certain stage to raise the
temperature to about 327° F. (164° C.). The pressure on the boiler
connected with the steam coil is raised to nearly seven atmospheres, and
thus the heat of the high-pressure steam rises to 327° F. (164° C.), and
then a considerable quantity of nitrate of ammonium, a crystallised
salt, is thrown into the water, in which it dissolves. Strange to say,
although the water alone would boil at 212° F., a strong solution in
water of the ammonium nitrate only boils at 327° F., so that the effect
of dissolving that salt in the water is the same as if the pressure were
raised to seven atmospheres. Now let us, as hat manufacturers, learn a
practical lesson from this fact. We have observed that wool and fur
fibres are injured by boiling in pure water, and the heat has much to do
with this damage; but if the boiling take place in bichrome liquors or
similar solutions, that boiling will, according to the strength of the
solution in dissolved matters, take place at a temperature more or less
elevated above the boiling-point of water, and so the damage done will
be the more serious the more concentrated the liquors are, quite
independently of the nature of the substances dissolved in those
liquors.

_Solution._--We have already seen that when a salt of any kind dissolves
in water, heat is absorbed, and becomes latent; in other words, cold is
produced. I will describe a remarkable example or experiment, well
illustrating this fact. If you take some Glauber's salt, crystallised
sulphate of soda, and mix it with some hydrochloric acid (or spirits of
salt), then so rapidly will the solution proceed, and consequently so
great will be the demand for heat, that if a vessel containing water be
put in amongst the dissolving salt, the heat residing in that vessel and
its water will be rapidly extracted, and the water will freeze. As
regards solubility, some salts and substances are much more quickly and
easily dissolved than others. We are generally accustomed to think that
to dissolve a substance quickly we cannot do better than build a fire
under the containing vessel, and heat the liquid. This is often the
correct method of proceeding, but not always. Thus it would mean simply
loss of fuel, and so waste of heat, to do this in dissolving ordinary
table salt or rock salt in water, for salt is as soluble in cold water
as in hot. Some salts are, incredible though it may appear, less soluble
in boiling water than in cold. Water just above the freezing-point
dissolves nearly twice as much lime as it does when boiling. You see,
then, that a knowledge of certain important facts like these may be so
used as to considerably mitigate your coal bills, under given
circumstances and conditions.



LECTURE IV

WATER: ITS CHEMISTRY AND PROPERTIES; IMPURITIES AND THEIR ACTION; TESTS
OF PURITY--_Continued_


In the last lecture, under the head of "Solution," I mentioned that some
salts, some chemical substances, are more soluble in water than others,
and that their solubilities under different circumstances of temperature
vary in different ways. However, some salts and compounds are
practically insoluble in water under any circumstances. We now arrive at
the important result known to chemists as the precipitation of insoluble
compounds from solutions. In order to define this result, however, we
must, of course, first consider the circumstances of causation of the
result. Let us take a simple case of chemical decomposition resulting in
the deposition or precipitation of a substance from solution in the
insoluble state. We will take a salt you are probably acquainted
with--sulphate of copper, or bluestone, and dissolve it in water, and we
have then the sulphate of copper in solution in water. Now suppose it is
our desire to obtain from that solution all the copper by depositing it
in some insoluble form. We may accomplish this in several different
ways, relying on certain methods of decomposing that sulphate of copper.
One of the simplest and most economical is that adopted in a certain
so-called wet method of extracting copper. It is based on the fact that
metallic iron has a greater tendency to combine in water solutions, with
the acids of copper salts, than the copper has in those salts. We
simply need to place some scraps of iron in the copper sulphate solution
to induce a change which may be represented as follows: Copper sulphate,
consisting of a combination of copper oxide with sulphuric acid, yields
with iron, iron sulphate, a combination of iron oxide with sulphuric
acid, and metallic copper. The metallic copper produced separates in the
form of a red coating on the iron scraps. But we may also, relying on
the fact that oxide of copper is insoluble in water, arrange for the
deposition of the copper in that form. This we can do by adding caustic
soda to a hot solution of copper sulphate, when we get the following
change: Copper sulphate, consisting of a combination of copper oxide
with sulphuric acid, yields with caustic soda, sulphate of soda, a
combination of soda with sulphuric acid and oxide of copper. Oxide of
copper is black, and so in this decomposition what is called a "black
precipitate" of that oxide is produced on adding the caustic soda. But
it might not suit us thus to deposit the copper from our solution; we
might desire to remove the sulphuric acid from the copper sulphate, and
leave the copper dissolved, say in the form of a chloride. We select,
then, a compound which is a chloride, and a chloride of a metal which
forms an insoluble combination with sulphuric acid--chloride of barium,
say. On adding this chloride of barium to sulphate of copper solution,
we get then a change which we might represent thus: Copper sulphate,
consisting of a combination of copper oxide with sulphuric acid, yields
with barium chloride, which is a combination of barium and chlorine,
insoluble barium sulphate, a combination of barium oxide with sulphuric
acid, and soluble copper chloride, a combination of copper and chlorine.
This is called a double interchange. Now these are a few illustrations
to show you what is meant by chemical decompositions. One practical
lesson, of course, we may draw is this: We must have a care in
dissolving bluestone or copper sulphate, not to attempt it in iron pans,
and not to store or put verdigris into iron vessels, or the iron will
be acted upon, and to some extent the copper salt will become
contaminated with iron. It will now be clear to you that, as a solvent
for bodies usually soluble in water, water that is perfectly pure will
be most suitable and not likely to cause any deposition or precipitation
through chemical decompositions, for there are no salts or other
compounds in pure water to cause such changes. Such pure water is called
soft water. But the term is only a comparative one, and water that is
not quite, but nearly pure--pure enough for most practical purposes--is
also called soft water. Now rain is the purest form of natural water,
for it is a kind of distilled water. Water rises in vapour from the
ocean as from a still, and the salt and other dissolved matters remain
behind. Meeting cold currents of air, the vapours condense in rain, and
fall upon the earth. After coming in contact with the earth, the
subsequent condition of that water entirely depends upon the character,
as regards solubility or insolubility, of the substances composing the
strata or layers of earth upon which it falls, and through which it
sinks. If it meets with insoluble rocks--for all rocks are not
insoluble--it remains, of course, pure and soft, and in proportion as
the constituents of rock and soil are soluble, in that proportion does
the water become hard. We all know how dangerous acid is in water,
causing that water to act on many substances, the iron of iron vessels,
the lime in soil or rock, etc., bringing iron and lime respectively into
solution. Now the atmosphere contains carbonic acid, and carbonic acid
occurs in the earth, being evolved by decomposing vegetation, etc.
Carbonic acid is also soluble to a certain, though not large extent, in
water. As we shall see, water charged with carbonic acid attacks certain
substances insoluble in pure water, and brings them into solution, and
thus the water soon becomes hard. About the close of the last lecture, I
said that lime is, to a certain extent, soluble in cold water. The
solution is called lime-water; it might be called a solution of caustic
lime. When carbonic acid gas first comes in contact with such a
solution, chalk or carbonate of lime, which is insoluble in water, is
formed, and the lime is thus precipitated as carbonate. Supposing,
however, we continued to pass carbonic acid gas into that water,
rendered milky with chalk powder, very soon the liquid would clear, and
we should get once more a solution of lime, but not caustic lime as it
was at first, simply now a solution of carbonate of lime in carbonic
acid, or a solution of bicarbonate of lime. I will take some lime-water,
and I will blow through; my breath contains carbonic acid, and you will
see the clear liquid become milky owing to separation of insoluble
carbonate of lime, or chalk. I now continue blowing, and at length that
chalk dissolves with the excess of carbonic acid, forming bicarbonate of
lime. This experiment explains how it is that water percolating through
or running over limestone strata dissolves out the insoluble chalk. Such
water, hard from dissolved carbonate of lime, can be softened by merely
boiling the water, for the excess of carbonic acid is then expelled, and
the chalk is precipitated again. This would be too costly for the
softening of large quantities of water, the boiling process consuming
too much coal, and so another process is adopted. Quicklime, or milk of
lime, is added to the water in the proper quantity. This lime unites
with the excess of carbonic acid holding chalk in solution, and forms
with it insoluble chalk, and so all deposits together as chalk. By this
liming process, also, the iron of the water dissolved likewise in
ferruginous streams, etc., by carbonic acid, would be precipitated. To
show this deposition I will now add some clear lime-water to the
solution I made of chalk with the carbonic acid of my breath, and a
precipitate is at once formed, all the lime and carbonic acid together
depositing as insoluble chalk. Hence clear lime-water forms a good test
for the presence of bicarbonates of lime or iron in a water. But water
may be hard from the presence of other salts, other lime salts. For
example, certain parts of the earth contain a great deal of gypsum, or
natural sulphate of lime, and this is soluble to some extent in water.
Water thus hardened is not affected by boiling, or the addition of lime,
and is therefore termed permanently hard water, the water hardened with
dissolved chalk being termed temporarily hard water. I have said nothing
of solid or undissolved impurities in water, which are said to be in
suspension, for the separation of these is a merely mechanical matter of
settling, or filtration and settling combined. As a general rule, the
water of rivers contains the most suspended and vegetable matter and the
least amount of dissolved constituents, whereas spring and well waters
contain the most dissolved matters and the least suspended. Serious
damage may be done to the dyer by either of these classes of impurities,
and I may tell you that the dissolved calcareous and magnesian
impurities are the most frequent in occurrence and the most injurious. I
told you that on boiling, the excess of carbonic acid holding chalk or
carbonate of lime in solution as bicarbonate, is decomposed and
carbonate of lime precipitated. You can at once imagine, then, what
takes place in your steam boilers when such water is used, and how
incrustations are formed. Let us now inquire as to the precise nature of
the waste and injury caused by hard and impure waters. Let us also take,
as an example, those most commonly occurring injurious constituents, the
magnesian and calcareous impurities. Hard water only produces a lather
with soap when that soap has effected the softening of the water, and
not till then. In that process the soap is entirely wasted, and the
fatty acids in it form, with the lime and magnesia, insoluble compounds
called lime and magnesia soaps, which are sticky, greasy, adhesive
bodies, that precipitate and fix some colouring matters like a mordant.
We have in such cases, then, a kind of double mischief--(i) waste of
soap, (ii) injury to colours and dyes on the fabrics. But this is not
all, for colours are precipitated as lakes, and mordants also are
precipitated, and thus wasted, in much the same sense as the soaps are.
Now by taking a soap solution, formed by dissolving a known weight of
soap in a known volume of water, and adding this gradually to hard water
until a permanent lather is just produced, we can directly determine the
consumption of soap by such a water, and ascertain the hardness. Such a
method is called Clark's process of determination or testing, or Clark's
soap test. We hear a great deal just now of soaps that will wash well in
hard water, and do wonders under any conditions; but mark this fact,
none of them will begin to perform effective duty until such hard water
has been rendered soft at the expense of the soap. Soaps made of some
oils, such as cocoa-nut oil, for example, are more soluble in water than
when made of tallow, etc., and so they more quickly soften a hard water
and yield lather, but they are wasted, as far as consumption is
concerned, to just the same extent as any other soaps. They do not,
however, waste so much time and trouble in effecting the end in view,
and, as you know, "Time is money" in these days of work and competition.
After making a soap test as described above, and knowing the quantity of
water used, it is, of course, easy to calculate the annual loss of soap
caused by the hardness of the water. The monthly consumption of soap in
London is 1,000,000 kilograms (about 1000 tons), and it is estimated
that the hardness of the Thames water means the use of 230,000 kilograms
(nearly 230 tons) more soap per month than would be necessary if soft
water were used. Of course the soap manufacturers around London would
not state that fact on their advertising placards, but rather dwell on
the victorious onslaught their particular brand will make on the dirt in
articles to be washed, in the teeth of circumstances that would be
hopeless for any other brand of soap! I have referred to the sticky and
adhesive character of the compounds called lime soaps, formed in hard
waters. Now in washing and scouring wool and other fibres, these sticky
lime soaps adhere so pertinaciously that the fibres, be they of wool,
silk, or any other article, remain in part untouched, impermeable to
mordant or colouring matter, and hence irregular development of colour
must be the consequence. Also an unnatural lustre or peculiar bloom may
in parts arise, ruining the appearance of the goods. In some cases the
lime soaps act like mordants, attracting colouring matter unequally, and
producing patchy effects. In the dye-baths in which catechu and tannin
are used, there is a waste of these matters, for insoluble compounds are
formed with the lime, and the catechu and tannin are, to a certain
extent, precipitated and lost. Some colours are best developed in an
acid bath, such as Cochineal Scarlet, but the presence of the
bicarbonate of lime tends to cause neutralisation of the acidity, and so
the dyeing is either retarded or prevented. Such mordants as "red
liquor" and "iron liquor," which are acetates of alumina and iron
respectively, are also wasted, a portion of them being precipitated by
the lime, thus weakening the mordant baths.

_Ferruginous Impurities in Water._--Iron in solution in water is very
objectionable in dyeing operations. When the iron is present as
bicarbonate, it acts on soap solutions like the analogous lime and
magnesia compounds, producing even worse results. In wool scouring,
cotton bleaching, and other processes requiring the use of alkaline
carbonates, ferric oxide is precipitated on the fibre. A yellowish tinge
is communicated to bleached fabrics, and to dye bright and light colours
is rendered almost out of the question. You may always suspect iron to
be present in water flowing from or obtained directly out of old coal
pits, iron mines, or from places abounding in iron and aluminous shales.
Moreover, you sometimes, or rather generally, find that surface water
draining off moorland districts, and passing over ochre beds, contains
iron, and on its way deposits on the beds of the streamlets conveying
it, and on the stones, red or brown oxide of iron. All water of this
kind ought to be avoided in dyeing and similar operations. The iron in
water from old coal pits and shale deposits is usually present as
sulphate due to the oxidation of pyrites, a sulphuret or sulphide of
iron. Water from heaths and moorlands is often acid from certain
vegetable acids termed "peaty acids." This acidity places the water in
the condition of a direct solvent for iron, and that dissolved iron may
cause great injury. If such water cannot be dispensed with, the best way
is to carefully neutralise it with carbonate of soda; the iron is then
precipitated as carbonate of iron, and can be removed.

_Contamination of Water by Factories._--You may have neighbours higher
up the stream than yourselves, and these firms may cast forth as waste
products substances which will cause immense waste and loss. Amongst
these waste products the worst are those coming from chemical works,
paper works, bleach works, etc. If the paper works be those working up
wood pulp, the pollutions of effluent water will be about as noxious as
they well can be. You will have gums and resins from the wood, calcium
chloride from the bleach vats, acids from the "sours"; resin, and
resin-soaps; there may also be alumina salts present. Now alumina, lime,
resin, and resin-soaps, etc., precipitate dyestuffs, and also soap; if
the water is alkaline, some of the mordants used may be precipitated and
wasted, and very considerable damage done.

Permanent hardness in water, due to the presence of gypsum or sulphate
of lime in solution, may be remedied by addition of caustic soda. Of
course, if an alkaline water is objectionable in any process, the alkali
would have to be neutralised by the addition of some acid. For use in
boilers, water might thus be treated, but it would become costly if
large quantities required such treatment. Water rendered impure by
contaminations from dyehouses and some chemical works can be best
purified, and most cheaply, by simple liming, followed by a settling
process. If space is limited and much water is required, instead of the
settling reservoirs, filtering beds of coke, sand, etc., may be used.
The lime used neutralises acids in the contaminated and impure water,
precipitates colouring matters, mordants, soap, albuminous matters, etc.

_Tests of Purity._--I will now describe a few tests that may be of value
to you in deciding as to what substances are contaminating any impure
waters that may be at hand.

_Iron._--If to a water you suspect to be hard from presence of carbonate
of lime or carbonate of iron in solution in carbonic acid, _i.e._ as
bicarbonates, you add some clear lime-water, and a white precipitate is
produced, you have a proof of carbonate of lime--hardness. If the
precipitate is brownish, you may have, also, carbonate of iron. I will
now mention a very delicate test for iron. Such a test would be useful
in confirmation. If a very dilute solution of such iron water be treated
with a drop or two of pure hydrochloric acid, and a drop or so of
permanganate of potash solution or of Condy's fluid, and after that a
few drops of yellow prussiate of potash solution be added, then a blue
colour (Prussian blue), either at once or after standing a few hours,
proves the presence of iron.

_Copper._--Sometimes, as in the neighbourhood of copper mines or of some
copper pyrites deposits, a water may be contaminated with small
quantities of copper. The yellow prussiate once more forms a good test,
but to ensure the absence of free mineral acids, it is first well to add
a little acetate of soda solution. A drop or two of the prussiate
solution then gives a brown colour, even if but traces of copper are
present.

_Magnesia._--Suppose lime and magnesia are present. You may first
evaporate to a small bulk, adding a drop of hydrochloric acid if the
liquid becomes muddy. Then add ammonia and ammonium oxalate, when lime
alone is precipitated as the oxalate of lime. Filter through blotting
paper, and to the clear filtrate add some phosphate of soda solution. A
second precipitation proves the presence of magnesia.

_Sulphates._--A solution of barium chloride and dilute hydrochloric acid
gives a white turbidity.

_Chlorides._--A solution of silver nitrate and nitric acid gives a white
curdy precipitate.

_Test for Lead in Drinking Water._--I will, lastly, give you a test that
will be useful in your own homes to detect minute quantities of lead in
water running through lead pipes. Place a large quantity of the water in
a glass on a piece of white paper, and add a solution of sulphuretted
hydrogen and let stand for some time. A brown colour denotes lead. Of
course copper would also yield a brown coloration, but I am supposing
that the circumstances preclude the presence of copper.

I have already said that rain water is the purest of natural waters; it
is so soft, and free from dissolved mineral matters because it is a
distilled water. In distilling water to purify it, we must be very
careful what material we use for condensing the steam in, since it is a
fact probably not sufficiently well known, that the softer and purer a
water is, the more liable it is to attack lead pipes. Hence a coil of
lead pipe to serve as condensing worm would be inadmissible. Such water
as Manchester water, and Glasgow water from Loch Katrine still more so,
are more liable to attack lead pipes than the hard London waters. To
illustrate this fact, we will distil some water and condense in a leaden
worm, then, on testing the water with our reagent, the sulphuretted
hydrogen water, a brown colour is produced, showing the presence of
lead. On condensing in a block tin worm, however, no tin is dissolved,
so tin is safer and better as the material for such a purpose than lead.

_Filtration._--We hear a great deal about filtration or filters as
universal means of purifying water. Filtration, we must remember, will,
as a rule, only remove solid or suspended impurities in water. For
example, if we take some ivory black or bone black, and mix it with
water and afterwards filter the black liquid through blotting-paper, the
bone black remains on the paper, and clear, pure water comes through.
Filtering is effective here. If we take some indigo solution, however,
and pour it on to the filter, the liquid runs through as blue as it was
when poured upon the filter. Filtering is ineffective here, and is so
generally with liquids containing matters dissolved in them. But I said
"generally," and so the question is suggested--Will filtration of any
kind remove matters in solution? This question I will, in conclusion,
try to answer. Bone charcoal, or bone black, has a wonderful attraction
for many organic matters such as colours, dyes, and coloured impurities
like those in peat water, raw sugar solutions, etc. For example, if we
place on a paper filter some bone black, and filter through it some
indigo solution, after first warming the latter with some more of the
bone black, the liquid comes through clear, all the indigo being
absorbed in some peculiar way, difficult to explain, by the bone black,
and remaining on the filter. This power of charcoal also extends to
gases, and to certain noxious dissolved organic impurities, but it is
never safe to rely too much on such filters, since the charcoal can at
length become charged with impurities, and gradually cease to act. These
filters need cleaning and renewing from time to time.



LECTURE V

ACIDS AND ALKALIS


_Properties of Acids and Alkalis._--The name acids is given to a class
of substances, mostly soluble in water, having an acid or sour taste,
and capable of turning blue litmus solution red. All acids contain one
or more atoms of hydrogen capable of being replaced by metals, and when
such hydrogen atoms are completely replaced by metals, there result
so-called neutral or normal salts, that is, neutral substances having no
action on litmus solution. These salts can also be produced by the union
of acids with equivalent quantities of certain metallic oxides or
hydroxides, called bases, of which those soluble in water are termed
alkalis. Alkalis have a caustic taste, and turn red litmus solution
blue.

In order to explain what is called the law of equivalence, I will remind
you of the experiment of the previous lecture, when a piece of bright
iron, being placed in a solution of copper sulphate, became coated with
metallic copper, an equivalent weight of iron meanwhile suffering
solution as sulphate of iron. According to the same law, a certain
weight of soda would always require a certain specific equivalent weight
of an acid, say hydrochloric acid, to neutralise its alkaline or basic
properties, producing a salt.

The specific gravities of acids and alkalis in solution are made use of
in works, etc., as a means of ascertaining their strengths and
commercial values. Tables have been carefully constructed, such that
for every degree of specific gravity a corresponding percentage strength
of acidity and alkalinity may be looked up. The best tables for this
purpose are given in Lunge and Hurter's _Alkali-Makers' Pocket-Book_,
but for ordinary purposes of calculation in the works or factory, a
convenient relationship exists in the case of hydrochloric acid between
specific gravity and percentage of real acid, such that specific gravity
as indicated by Twaddell's hydrometer directly represents percentage of
real acid in any sample of hydrochloric acid.

The point at which neutralisation of an acid by alkali or _vice versâ_
just takes place is ascertained very accurately by the use of certain
sensitive colours. At first litmus and cochineal tinctures were used,
but in testing crude alkalis containing alumina and iron, it was found
that lakes were formed with these colours, and they become precipitated
in the solution, and so no longer sensitive. The chemist was then
obliged to resort to certain sensitive coal-tar colours, which did not,
as the dyer and printer knew, form lakes with alumina and iron, such as
methyl orange, fluorescein, Congo red, phenolphthalein, and so forth.
For determining the alkalimetric strength of commercial sodas, a known
weight of the sample is dissolved in water, and a few drops of a
solution of methyl orange are added, which colour the solution yellow or
orange. Into this solution is then run, from a burette or graduated
tube, a standard solution of an acid, that is, a solution prepared by
dissolving a known weight of an acid, say hydrochloric acid, in a known
volume of water. The acid is run in gradually until the yellow colour
changes to pink, at which point the volume of acid used is noted.
Knowing the weight of acid contained in this volume of standard acid,
and having regard to the law of equivalence mentioned above, it is an
easy matter to calculate the amount of alkali equivalent to the acid
used, and from this the alkali contained in the sample.

_Sulphuric Acid._--The first process for manufacturing sulphuric acid or
vitriol was by placing some burning sulphur in a closed vessel
containing some water. The water absorbed the acid formed by the burning
sulphur. It was next discovered that by mixing with the sulphur some
nitre, much more sulphuric acid could be produced per given quantity of
brimstone. At first large glass carboys were used, but in 1746 the
carboys were replaced by chambers of lead containing water at the
bottom, and in these lead chambers the mixture of sulphur and nitre was
burnt on iron trays. Next, although gradually, the plant was divided
into two portions--a furnace for burning the sulphur, and a chamber for
receiving the vapours. The system was thus developed into the one
followed at the present time. The sulphur, or, in most cases, cupreous
iron pyrites (a combination of iron and copper with sulphur), is burned
in specially constructed kilns or furnaces, and the hot gases,
consisting essentially of sulphur dioxide with the excess of air, pass
through flues in which are placed cast-iron "nitre pots" containing a
mixture of nitre (sodium nitrate) and vitriol. The gases thus become
mixed with nitrous fumes or gaseous oxides of nitrogen, and, after
cooling, are ready for mixing with steam or water spray in the lead
chambers in which the vitriol is produced. These oxides of nitrogen
enable the formation of sulphuric acid to take place more quickly by
playing the part of oxygen-carriers. Sulphuric acid is formed by the
union of oxygen with sulphur dioxide and water; the oxides of nitrogen
combine with the oxygen of the air present in the chambers, then give up
this oxygen to the sulphur dioxide and water or steam to form sulphuric
acid, again combine with more oxygen, and so on. The exact processes or
reactions are of course much more complicated, but the above represents
what is practically the ultimate result. It is evident that the gases
leaving the last lead chamber in which the formation of vitriol is
effected, must still contain nitrous fumes, and it becomes a matter of
importance to recover them, so that they can be used over again. To
effect this object, use is made of the solubility of nitrous fumes in
strong vitriol. The gases from the last lead chamber of the series are
passed through what is called a Gay-Lussac tower (the process was
invented by the eminent French chemist Gay-Lussac), which is a tower
made of lead, supported by a wooden framework, and filled with coke or
special stoneware packing, over which strong vitriol is caused to flow.
The vitriol dissolves the nitrogen oxides, and so-called "nitrous
vitriol" flows out at the base of the tower. The recovery of the
nitrogen compounds from the nitrous vitriol is effected in Glover towers
(the invention of John Glover of Newcastle), which also serve to
concentrate to some extent the weak acid produced in the lead chambers,
and to cool the hot gases from the sulphur burners or pyrites kilns. The
weak chamber acid is mixed with the nitrous vitriol from the Gay-Lussac
tower, and the mixture is pumped to the top of the Glover tower, which
is of similar construction to the Gay-Lussac tower, but is generally
packed with flints. This Glover tower is placed between the sulphur
burners or pyrites kilns and the first lead chamber. The nitrous vitriol
passing down the tower meets the hot gases from the kilns, and a
threefold object is effected: (1) The nitrous fumes are expelled from
the nitrous vitriol, and are carried into the chambers, to again play
the part of oxygen-carriers; (2) the weak chamber acid which was mixed
with the nitrous vitriol is concentrated by the hot kiln gases; and (3)
the hot gases themselves are cooled. The acid from the Glover tower is
purified by special treatment--for example, the arsenic may be removed,
after precipitation with sulphuretted hydrogen, in the form of insoluble
arsenic sulphide,--and the purified acid is concentrated by heating in
glass or platinum vessels.

A considerable amount of sulphuric acid is now made by the so-called
"contact process," in which sulphur dioxide and oxygen unite to form
sulphuric acid in presence of a heated "contact" substance, usually some
form of finely-divided platinum.

_Nitric Acid._--This acid is usually prepared by distilling a mixture of
sodium nitrate and vitriol in cast-iron retorts or pots, the nitric acid
being collected in stoneware vessels connected one with another, or, as
is more generally the case at the present time, in condensing apparatus
consisting of stoneware pipes or coils cooled by water. The effluent
gases are passed through a scrubber in order to free them from the last
traces of acid before discharging them into the atmosphere.

_Hydrochloric Acid._--The greater part of the hydrochloric acid
manufactured in Great Britain is obtained as an intermediate product in
the Leblanc alkali process, which will presently be described, being
produced by heating common salt with vitriol. A large quantity is,
however, also produced by the so-called direct process of Hargreaves &
Robinson, which is, in principle, the same method as that employed in
the Leblanc process, except that the intermediate product, vitriol, is
not separated. It consists essentially in passing the hot gases from
pyrites kilns, as used in the manufacture of vitriol, through large
cast-iron vessels containing common salt heated to a high temperature.
Various physical conditions must be complied with in order to make the
process a success. For example, the salt is used in the form of moulded
hard porous cakes made from a damp mixture of common salt and rock salt.
The cast-iron vessels must be heated uniformly, and the hot pyrites kiln
gases must be passed downwards through the salt in order to ensure
uniform distribution. The hydrochloric acid is condensed in stoneware
pipes connected with towers packed with coke or stoneware.

_Alkali: Leblanc Process._--The manufacture of vitriol, as I have
described it to you, is the first step in the Leblanc process. The next
stage consists in the manufacture of sodium sulphate (salt-cake) and
hydrochloric acid from the sulphuric acid and common salt; this is
called the salt-cake process. The production of salt-cake or crude
sodium sulphate is carried out in two stages. A large covered iron pan,
called the decomposing pan or salt-cake pot, is mounted in one part of
the salt-cake furnace, and alongside it is the hearth or bed on which
the second stage of the process, the drying or roasting, is effected.
The mixture of common salt and vitriol is charged into the salt-cake
pot, which is heated by a fire below. When from two-thirds to
three-quarters of the hydrochloric acid has been expelled from the
charge, the mass acquires the consistence of thick dough, and at this
stage it is raked out of the pan on to the roasting hearth alongside,
where the decomposition is completed by means of flames playing directly
on to the top of the charge. The hydrochloric acid evolved during the
process is condensed in much the same manner as in the process of
Hargreaves & Robinson previously described. It is a curious fact that in
the earlier years of the Leblanc process, hydrochloric acid, or "spirits
of salt," as it is frequently called, was a by-product that required all
the vigilance of the alkali-works inspectors to prevent it being allowed
to escape from the chimneys in more than a certain small regulated
amount. Now, it is the principal product; indeed, the Leblanc alkali
maker may be said to subsist on that hydrochloric acid, as his chief
instrument for producing chloride of lime or bleaching powder.

Mechanical furnaces are now used to a large extent for the salt-cake
process. They consist broadly of a large revolving furnace-hearth or
bed, on to which the mixture of salt and vitriol is charged, and on
which it is continuously agitated, and gradually moved to the place of
discharge, by rakes or the like, operated by suitable machinery.

The next stage of the Leblanc process is the manufacture of "black ash,"
or crude sodium carbonate. This is usually done in large cylindrical
revolving furnaces, through, which flames from a fire-grate, or from the
burning of gaseous fuel, pass; the waste heat is utilised for boiling
down "black ash" liquor, obtained by lixiviating the black ash. A
mixture of salt-cake, limestone or chalk (calcium carbonate), and
powdered coal or coal slack is charged into the revolving cylinder;
during the process the mass becomes agglomerated, and the final product
is what is known as a "black-ash ball," consisting chiefly of crude
sodium carbonate and calcium sulphide, but containing smaller quantities
of many other substances. The soda ash or sodium carbonate is obtained
from the black ash by lixiviating with water, and after various
purification processes, the solution is boiled down, as previously
stated, by the waste heat of the black-ash furnace. The alkali is sold
in various forms as soda ash, soda crystals, washing soda, etc.

Caustic soda is manufactured from solution of carbonate of soda by
causticising, that is, treatment with caustic lime or quicklime.

It will have been noticed that one of the chief reagents in the Leblanc
process is the sulphur used in the form of brimstone or as pyrites for
making vitriol in the first stage; this sulphur goes through the entire
process; from the vitriol it goes to form a constituent of the
salt-cake, and afterwards of the calcium sulphide contained in the black
ash. This calcium sulphide remains as an insoluble mass when the
carbonate of soda is extracted from the black ash, and forms the chief
constituent of the alkali waste, which until the year 1880 could be seen
in large heaps around chemical works. Now, however, by means of
treatment with kiln gases containing carbonic acid, the sulphur is
extracted from the waste in the form of hydrogen sulphide, which is
burnt to form vitriol, or is used for making pure sulphur; and so what
was once waste is now a source of profit.

_Ammonia-Soda Process of Alkali Manufacture._--This process depends
upon the fact that when carbonic acid is forced, under pressure, into a
saturated solution of ammonia and common salt, sodium bicarbonate is
precipitated, whilst ammonium chloride or "sal-ammoniac" remains
dissolved in the solution. The reaction was discovered in 1836 by a
Scotch chemist named John Thom, and small quantities of ammonia-soda
were made at that time by the firm of McNaughton & Thom. The successful
carrying out of the process on the large scale depends principally upon
the complete recovery of the expensive reagent, ammonia, and this
problem was only solved within comparatively recent years by Solvay. The
process has been perfected and worked with great success in England by
Messrs. Brunner, Mond, & Co., and has proved a successful rival to the
Leblanc process.

Alkali is also produced to some extent by electrolytic processes,
depending upon the splitting up of a solution of common salt into
caustic soda and chlorine by the use of an electric current.



LECTURE VI

BORIC ACID, BORAX, SOAP


_Boric Acid._--At ordinary temperatures and under ordinary conditions
boric acid is a very weak acid, but like silicic and some other acids,
its relative powers of affinity and combination become very much changed
at high temperatures; thus, fused and strongly heated boric acid can
decompose carbonates and even sulphates, and yet a current of so weak an
acid as hydrogen sulphide, passed through a strong solution of borax,
will decompose it and set free boric acid. Boric acid is obtained
chiefly from Italy. In a tract of country called the Maremma of Tuscany,
embracing an area of about forty square miles, are numerous chasms and
crevices, from which hot vapour and heated gases and springs of water
spurt. The steam issuing from these hot springs contains small
quantities of boric acid, that acid being one of those solid substances
distilling to some extent in a current of steam. The steam vapours thus
bursting forth, owing to some kind of constant volcanic disturbance, are
also more or less laden with sulphuretted hydrogen gas, communicating a
very ill odour to the neighbourhood. These phenomena were at first
looked upon by the people as the work of the devil, and priestly
exorcisms were in considerable request in the hope of quelling them,
very much as a great deal of the mere speech-making at the present time
in England on foreign competition and its evils, and the dulness of
trade, the artificial combinations to keep up prices, to reduce wages,
general lamentation, etc., are essayed in the attempt to charm away bad
trade. At length a kind of prophet arose of a very practical character
in the form of the late Count Lardarel, who, mindful of the fact that
the chemist Höffer, in the time of the Grand Duke Leopold I., had
discovered boric acid in the volcanic steam jets, looked hopefully
beyond the exorcisms of the priests and the superstitions of the people
to a possible blessing contained in what appeared to be an unholy
confusion of Nature. He constructed tanks of from 100 to 1000 ft. in
diameter and 7 to 20 ft. in depth, of such a kind that the steam jets
were surrounded by or contained in them, and thus the liquors formed by
condensation became more and more concentrated. These tanks were
arranged at different levels, so that the liquors could be run off from
one to the other, and finally to settling cisterns. Subsequently the
strong liquors were run to lead-lined, wooden vats, in which the boric
acid was crystallised out. Had the industry depended on the use of fuel
it could never have developed, but Count Lardarel ingeniously utilised
the heat of the steam for all the purposes, and neither coal nor wood
was required. Where would that Tuscan boric acid industry have been now
had merely the lamentations of landowners, fears of the people, and
exorcisms of the priests been continued? Instead of being the work of
the arch-enemy of mankind, was not it rather an incitement to a somewhat
high and difficult step in an upward direction towards the attainment,
on a higher platform of knowledge and skill, of a blessing for the whole
province of Tuscany? What was true in the history of that industry and
its development is every whit as true of the much-lamented slackening of
trade through foreign competition or other causes now in this country,
and coming home to yourselves in the hat-manufacturing industry. The
higher platform to which it was somewhat difficult to step up, but upon
which the battle must be fought and the victory won, was one of a higher
scientific and technological education and training. The chemist Höffer
made the discovery of boric acid in the vapours, they would no doubt
take note; but Höffer went no further; and it needed the man of both
educated and practical mind like Count Lardarel to turn the discovery to
account and extract the blessing. In like manner it was clear that in
our educational schemes for the benefit of the people, there must not
only be the scientific investigator of abstract truth, but also the
scientific technologist to point the way to the practical realisation of
tangible profit. Moreover, and a still more important truth, it is the
scientific education of the proprietors and heads we want--educated
capital rather than educated workmen.

_Borax._--A good deal of the Tuscan boric acid is used in France for the
manufacture of borax, which is a sodium salt of boric acid. Borax is
also manufactured from boronitrocalcite, a calcium salt of boric acid,
which is found in Chili and other parts of South America. The crude
boronitrocalcite or "tiza" is boiled with sodium carbonate solution,
and, after settling, the borax is obtained by crystallisation. Borax
itself is found in California and Nevada, U.S.A., and also in Peru,
Ceylon, China, Persia, and Thibet. The commercial product is obtained
from the native borax (known as "tincal") by dissolving in water and
allowing the solution to crystallise. The Peruvian borax sometimes
contains nitre. For testing the purity of refined borax the following
simple tests will usually suffice. A solution of the borax is made
containing 1 part of borax to 50 parts of water, and small portions of
the solution are tested as follows: _Heavy metals_ (_lead_, _copper_,
etc.).--On passing sulphuretted hydrogen into the solution, no
coloration or precipitate should be produced. _Calcium Salts._--The
solution should not give a precipitate with ammonium oxalate solution.
_Carbonates._--The solution should not effervesce on addition of nitric
or hydrochloric acid. _Chlorides._--No appreciable precipitate should
be produced on addition of silver nitrate solution and nitric acid.
_Sulphates._--No appreciable precipitate should be produced on adding
hydrochloric acid and barium chloride. _Iron._--50 c.c. of the solution
should not immediately be coloured blue by 0·5 c.c. of potassium
ferrocyanide solution.

_Soap._--Soap is a salt in the chemical sense, and this leads to a wider
definition of the term "salt" or "saline" compound. Fats and oils, from
which soaps are manufactured, are a kind of _quasi_ salts, composed of a
fatty acid and a chemical constant, if I may use the term, in the shape
of base, namely, glycerin. When these fats and oils, often called
glycerides, are heated with alkali, soda, a true salt of the fatty acid
and soda is formed, and this is the soap, whilst the glycerin remains
behind in the "spent soap lye." Now glycerin is soluble in water
containing dissolved salt (brine), whilst soap is insoluble, though
soluble in pure water. The mixture of soap and glycerin produced from
the fat and soda is therefore treated with brine, a process called
"cutting the soap." The soap separates out in the solid form as a curdy
mass, which can be easily separated. Certain soaps are able to absorb a
large quantity of water, and yet appear quite solid, and in purchasing
large quantities of soap it is necessary, therefore, to determine the
amount of water present. This can be easily done by weighing out ten or
twenty grams of the soap, cut in small pieces, into a porcelain dish and
heating over a gas flame, whilst keeping the soap continually stirred,
until a glass held over the dish no longer becomes blurred by escaping
steam. After cooling, the dry soap is weighed, and the loss of weight
represents the amount of moisture. I have known cases where soap
containing about 83 per cent. of water has been sold at the full market
price. Some soaps also contain more alkali than is actually combined
with the fatty acids of the soap, and that excess alkali is injurious in
washing silks and scouring wool, and is also not good for the skin. The
presence of this free or excess alkali can be at once detected by
rubbing a little phenolphthalein solution on to the freshly-cut surface
of a piece of soap; if free alkali be present, a red colour will be
produced.



LECTURE VII

SHELLAC, WOOD SPIRIT, AND THE STIFFENING AND PROOFING PROCESS


_Shellac._--The resin tribe, of which shellac is a member, comprises
vegetable products of a certain degree of similarity. They are mostly
solid, glassy-looking substances insoluble in water, but soluble in
alcohol and wood spirit. In many cases the alcoholic solutions show an
acid reaction. The resins are partly soluble in alkalis, with formation
of a kind of alkali salts which we may call resin-soaps.

Shellac is obtained from the resinous incrustation produced on the bark
of the twigs and branches of various tropical trees by the puncture of
the female "lac insect" (_Taccardia lacca_). The lac is removed from the
twigs by "beating" in water; the woody matter floats to the surface, and
the resin sinks to the bottom, and when removed forms what is known as
"seed-lac." Formerly, the solution, which contains the colouring matter
dissolved from the crude "stick-lac," was evaporated for recovery of the
so-called "lac-dye," but the latter is no longer used technically. The
seed-lac is bleached by boiling with sodium or potassium carbonate,
alum, or borax, and then, if it is not pale enough, is further bleached
by exposure to sunlight. It is now dried, melted, and mixed with a
certain proportion of rosin or of orpiment (a sulphide of arsenic)
according to the purpose for which it is desired. After further
operations of melting and straining, the lac is melted and spread into
thin sheets to form ordinary shellac, or is melted and dropped on to a
smooth surface to form "button-lac." Ordinary shellac almost invariably
contains some rosin, but good button-lac is free from this substance.
The presence of 5 per cent. of rosin in shellac can be detected by
dissolving in a little alcohol, pouring the solution into water, and
drying the fine impalpable powder which separates. This powder is
extracted with petroleum spirit, and the solution shaken with water
containing a trace of copper acetate. If rosin be present, the petroleum
spirit will be coloured emerald-green.

Borax, soda crystals, and ammonia are all used to dissolve shellac, and
it may be asked: Which of these is least injurious to wool? and why? How
is their action modified by the presence of dilute sulphuric acid in the
wool? I would say that soda crystals and ammonia are alkalis, and if
used strong, are sure to do a certain amount of injury to the fibre of
wool, and more if used hot than cold. Of the two, the ammonia will have
the least effect, especially if dilute, but borax is better than either.
The influence of a little sulphuric acid in the wool would be in the
direction of neutralising some of the ammonia or soda, and shellac, if
dissolved in the alkalis, would be to some extent precipitated on the
fibre, unless the alkali, soda or ammonia, were present in sufficient
excess to neutralise that sulphuric acid and to leave a sufficient
balance to keep the shellac in solution. Borax, which is a borate of
soda, would be so acted on by the sulphuric acid that some boric acid
would be set free, the sulphuric acid robbing some of that borax of its
soda. This boric acid would not be nearly so injurious to wool as
carbonate of soda or ammonia would.

The best solvent for shellac, however, in the preparation of the
stiffening and proofing mixture for hats, is probably wood spirit or
methylated spirit. A solution of shellac in wood spirit is indeed used
for the spirit-proofing of silk hats, and to some extent of felt hats,
and on the whole the best work, I believe, is done with it. Moreover,
borax is not a cheap agent, and being non-volatile it is all left behind
in the proofed material, whereas wood spirit or methylated spirit is a
volatile liquid, _i.e._ a liquid easily driven off in vapour, and after
application to the felt it may be almost all recovered again for re-use.
In this way I conceive the use of wood spirit would be both more
effective and also cheaper than that of borax, besides being most
suitable in the case of any kind of dyes and colours to be subsequently
applied to the hats.

_Wood Spirit._--Wood spirit, the pure form of which is methyl alcohol,
is one of the products of the destructive distillation of wood. The wood
is distilled in large iron retorts connected to apparatus for condensing
the distillation products. The heating is conducted slowly at first, so
that the maximum yield of the valuable products--wood acid (acetic acid)
and wood spirit--which distil at a low temperature, is obtained. When
the condensed products are allowed to settle, they separate into two
distinct layers, the lower one consisting of a thick, very dark tar,
whilst the upper one, much larger in quantity, is the crude wood acid
(containing also the wood spirit), and is reddish-yellow or
reddish-brown in colour. This crude wood acid is distilled, and the wood
spirit which distils off first is collected separately from the acetic
acid which afterwards comes over. The acid is used for the preparation
of alumina and iron mordants (see next lecture), or is neutralised with
lime, forming grey acetate of lime, from which, subsequently, pure
acetic acid or acetone is prepared. The crude wood spirit is mixed with
milk of lime, and after standing for several hours is distilled in a
rectifying still. The distillate is diluted with water, run off from any
oily impurities which are separated, and re-distilled once or twice
after treatment with quicklime.

_Stiffening and Proofing Process._--Before proceeding to discuss the
stiffening and proofing of hat forms or "bodies," it will be well to
point out that it was in thoroughly grasping the importance of a
rational and scientific method of carrying out this process that
Continental hat manufacturers had been able to steal a march upon their
English rivals in competition as to a special kind of hat which sold
well on the Continent. There are, or ought to be, three aims in the
process of proofing and stiffening, all the three being of equal
importance. These are: first, to waterproof the hat-forms; second, to
stiffen them at the same time and by the same process; and the third,
the one the importance of which I think English hat manufacturers have
frequently overlooked, at least in the past, is to so proof and stiffen
the hat-forms as to leave them in a suitable condition for the
subsequent dyeing process. In proofing the felt, the fibres become
varnished over with a kind of glaze which is insoluble in water, and
this varnish or proof is but imperfectly removed from the ends of the
fibres on the upper surface of the felt. The consequence is a too slight
penetration of the dyestuff into the inner pores of the fibres; indeed,
in the logwood black dyeing of such proofed felt a great deal of the
colour becomes precipitated on the outside of the fibres--a kind of
process of "smudging-on" of a black pigment taking place. The subsequent
"greening" of the black hats after a short period of wear is simply due
to the ease with which such badly fixed dye rubs off, washes off, or
wears off, the brownish or yellowish substratum which gradually comes to
light, causing a greenish shade to at length appear. If we examine under
the microscope a pure unproofed fur fibre, its characteristic structure
is quite visible. Examination of an unproofed fibre dyed with logwood
black shows again the same characteristic structure with the dye inside
the fibre, colouring it a beautiful bluish-grey tint, the inner cellular
markings being black. A proofed fur fibre, on the other hand, when
examined under the microscope, is seen to be covered with a kind of
translucent glaze, which completely envelops it, and prevents the
beautiful markings showing the scaly structure of the fibre from being
seen. Finally, if we examine microscopically a proofed fibre which has
been dyed, or which we have attempted to dye, with logwood black, we
find that the fibre presents an appearance similar to that of rope which
has been drawn through some black pigment or black mud, and then dried.
It is quite plain that no lustrous appearance or good "finish" can be
expected from such material. Now how did the Continental hat
manufacturers achieve their success, both as regards dyeing either with
logwood black or with coal-tar colours, and also getting a high degree
of "finish"? They attained their object by rubbing the proofing varnish
on the inside of the hat bodies, in some cases first protecting the
outside with a gum-varnish soluble in water but resisting the
lac-varnish rubbed inside. Thus the proofing could never reach the
outside. On throwing the hat bodies, thus proofed by a logical and
scientific process, into the dye-bath, the gums on the outer surface are
dissolved and removed, and the dye strikes into a pure, clean fibre,
capable of a high degree of finish. This process, however, whilst very
good for the softer hats used on the Continent, is not so satisfactory
for the harder, stiffer headgear demanded in Great Britain. What was
needed was a process which would allow of a through-and-through proofing
and stiffening, and also of satisfactory dyeing of the stiffened and
proofed felt. This was accomplished by a process patented in 1887 by Mr.
F.W. Cheetham, and called the "veneering" process. The hat bodies,
proofed as hard as usual, are thrown into a "bumping machine" containing
hot water rendered faintly acid with sulphuric acid, and mixed with
short-staple fur or wool, usually of a finer quality than that of which
the hat bodies are composed. The hot acid water promotes in a high
degree the felting powers of the short-staple wool or fur, and, to a
lesser extent, the thinly proofed ends of the fibres projecting from
the surfaces of the proofed hat-forms. Thus the short-staple wool or fur
felts itself on to the fibres already forming part of the hat bodies,
and a new layer of pure, unproofed wool or fur is gradually wrought on
to the proofed surface. The hat-forms are then taken out and washed, and
can be dyed with the greatest ease and with excellent results, as will
be seen from the accompanying illustration (see Fig. 15). This
successful invention emphasises the value of the microscope in the
study of processes connected with textile fibres. I would strongly
advise everyone interested in hat manufacturing or similar industries to
make a collection of wool and fur fibres, and mount them on microscope
slides so as to form a kind of index collection for reference.

[Illustration: FIG. 15.

     1. Natural wool fibre unproofed.

     2. Wool fibre showing proof on surface, filling up the cells
     and rendering the same dye-proof.

     3. Fur fibre from surface of veneered felt, showing dye
     deposited in cells and on the surface, bright and lustrous.

     4. Wool fibre as in No. 2, with dye deposited on surface of
     proof.

     5. Section of proofed and veneered body, showing unproofed
     surface.

     6. Section of proofed body without "veneer."]



LECTURE VIII

MORDANTS: THEIR NATURE AND USE


The name or word "mordant" indicates the empiricism, or our old friend
"the rule of thumb," of the age in which it was first created and used.
It serves as a landmark of that age, which, by the way, needed
landmarks, for it was an age of something between scientific twilight
and absolute darkness. _Morder_ in French, derived from the Latin
_mordere_, means "to bite," and formerly the users of mordants in dyeing
and printing believed their action to be merely a mechanical action,
that is, that they exerted a biting or corroding influence, serving to
open the pores of the fabrics, and thus to give more ready ingress to
the colour or dye.

Most mordants are salts, or bodies resembling salts, and hence we must
commence our study of mordants by a consideration of the nature of
salts. I have already told you that acids are characterised by what we
term an acid reaction upon certain vegetable and artificial colours,
whilst bases or basic substances in solution, especially alkalis,
restore those colours, or turn them to quite another shade; the acids do
the one thing, and the alkalis and soluble bases do the opposite. The
strongest and most soluble bases are the alkalis--soda, potash, and
ammonia. You all know, probably, that a drop of vitriol allowed to fall
on a black felt hat will stain that hat red if the hat has been dyed
with logwood black; and if you want to restore the black, you can do
this by touching the stain with a drop of strong ammonia. But the use
of a black felt hat as a means of detecting acidity or alkalinity would
not commend itself to an economic mind, and we find a very excellent
reagent for the purpose in extract of litmus or litmus tincture, as well
as in blotting paper stained therewith. The litmus is turned bright red
by acids and blue by alkalis. If the acid is exactly neutralised by,
that is combined with, the alkaline base to form fully neutralised
salts, the litmus paper takes a purple tint. Coloured reagents such as
litmus are termed indicators. A substance called phenolphthalein, a
coal-tar product, is a very delicate indicator; it is more sensitive to
acids than litmus is. Now there are some salts which contain a
preponderance of acid in their composition, _i.e._ in which the acid has
not been fully neutralised by the base; such salts are termed acid
salts. Bicarbonate of soda is one of these acid salts, but so feeble is
carbonic acid in its acid properties and practical evidences, that we
shall see both monocarbonate or "neutral" carbonate of soda and
bicarbonate or "acid" carbonate of soda show evidences of, or, as
chemists say, react with alkalinity towards litmus. However,
phenolphthalein, though reacting alkaline with monocarbonate of soda,
indicates the acidity of the bicarbonate of soda, a thing which, as I
have just said, litmus will not do. We will take two jars containing
solution of monocarbonate of soda, and in the first we will put some
phenolphthalein solution, and in the second, some litmus tincture. The
solution in the first jar turns rose coloured, and in the second, blue,
indicating in each case that the solution is alkaline. If now, however,
carbonic acid be blown into the two solutions, that in the first jar,
containing the phenolphthalein, becomes colourless as soon as the
monocarbonate of soda is converted into bicarbonate, and this
disappearance of the rose colour indicates acidity; the blue solution in
the jar containing litmus, on the other hand, is not altered by blowing
in carbonic acid. Furthermore, if to the colourless solution containing
phenolphthalein, and which is acid towards that reagent, a little
reddened litmus is added, this is still turned blue, and so still
indicates the presence of alkali. We have, therefore, in bicarbonate of
soda a salt which behaves as an acid to phenolphthalein and as an alkali
to litmus. Another extremely sensitive indicator is the coal-tar
dyestuff known as "Congo red"; the colour changes produced by it are
exactly the inverse of those produced in the case of litmus, that is, it
gives a blue colour with acids and a red colour with alkalis.

We have now learned that acids are as the antipodes to alkalis or bases,
and that the two may combine to form products which may be neutral or
may have a preponderance either of acidity or of basicity--in short,
they may yield neutral, acid, or basic salts. I must try to give you a
yet clearer idea of these three classes of salts. Now acids in general
have, as we have seen, what we may call a "chemical appetite," and each
acid in particular has a "specific chemical appetite" for bases, that
is, each acid is capable of combining with a definite quantity of an
individual base. The terms "chemical appetite" and "specific chemical
appetite" are names I have coined for your present benefit, but for
which chemists would use the words "affinity" and "valency"
respectively. Now some acids have a moderate specific appetite, whilst
others possess a large one, and the same may be said of bases, and thus
as an example we may have mono-, di-, and tri-acid salts, or mono-, di-,
and tri-basic salts. In a tri-acid salt a certain voracity of the base
is indicated, and in a tri-basic salt, of the acid. Again, with a base
capable of absorbing and combining with its compound atom or molecule
several compound atoms or molecules of an acid, we have the possibility
of partial saturation, and, perhaps, of several degrees of it, and also
of full saturation, which means combination to the full extent of the
powers of the base in question. Also, with an acid capable of, or
possessing a similar large absorptive faculty for bases, we have
possibilities of the formation of salts of various degrees of basicity,
according to the smaller or larger degree of satisfaction given to the
molecule of such acid by the addition of a base. We will now take as a
simple case that of hydrochloric acid (spirits of salt), which is a
monobasic acid, that is, its molecule is capable of combining with only
one molecule of a monoacid base. Hydrochloric acid may be written, as
its name would indicate, HCl, and an addition even of excess of such a
base as caustic soda (written NaOH) would only yield what is known as
common salt or chloride of sodium (NaCl), in which the metal sodium (Na)
has replaced the hydrogen (H) of the hydrochloric acid. Now chloride of
sodium when dissolved in water will turn litmus neither blue nor red; it
is therefore neutral. Such simple, neutral, monobasic salts are mostly
very stable. By "stable" we mean they possess considerable resistance to
agencies, that, in the case of other salts, effect decompositions of
those salts. Such other salts which are decomposed more or less readily
are termed "unstable," but the terms are of course only comparative.

Now let us consider a di- or bi-basic acid. Such an one is vitriol or
sulphuric acid (H_{2}SO_{4}). The hydrogen atoms are in this case an
index of the basicity of the acid, and accordingly the fully saturated
sodium salt is Na_{2}SO_{4} or neutral, or better normal, sulphate of
soda. In like manner the fully saturated salt of the dibasic acid,
carbonic acid (H_{2}CO_{3}), is Na_{2}CO_{3}, ordinary or normal
carbonate of soda. But we must observe that with these dibasic acids it
is possible, by adding insufficient alkali to completely saturate them,
to obtain salts in which only one hydrogen atom of the acid is replaced
by the metal of the base. Thus sulphuric and carbonic acids yield
NaHSO_{4}, acid sulphate or bisulphate of soda, and NaHCO_{3},
bicarbonate of soda, respectively. An example of a tribasic acid is
phosphoric acid, H_{3}PO_{4}, and here we may have three different
classes of salts of three various degrees of basicity or
base-saturation. We may have the first step of basicity due to
combination with soda, NaH_{2}PO_{4}, or monosodium phosphate, the
second step, Na_{3}HPO_{4}, or disodium phosphate, and the third, and
final step, Na_{3}PO_{4}, or trisodium phosphate. Now let us turn to the
varying degrees of acidity, or rather the proportions of acid radicals
in salts, due to the varying appetites or combining powers of bases.
Sodium only forms simple monoacid salts, as sodium chloride (NaCl),
sodium sulphate (Na_{2}SO_{4}); calcium forms diacid salts, _e.g._
calcium chloride (CaCl_{2}); and aluminium and iron, triacid salts, for
example, aluminium sulphate [Al_{2}(SO_{4})_{3}] and iron (ferric)
sulphate [Fe_{2}(SO_{4})_{3}]. Now in these triacid salts we can remove
some of the acid groups and substitute the elements of water, OH, or
hydroxyl, as it is called, for them. Such salts, then, only partly
saturated with acid, are termed basic salts. Thus we have
Al_{2}(OH)_{2}(SO_{4})_{2}, Al_{2}(OH)_{4}SO_{4}, as well as
Al_{2}(SO_{4})_{3}, and we can get these basic salts by treating the
normal sulphate [Al_{2}(SO_{4})_{3}] with sufficient caustic soda to
remove the necessary quantities of sulphuric acid. Now it is a curious
thing that of these aluminium sulphates the fully saturated one,
Al_{2}(SO_{4})_{3}, is the most stable, for even on long boiling of its
solution in water it suffers no change, but the more basic is the
sulphate the less stable it becomes, and so the more easily it
decomposes on heating or boiling its solution, giving a deposit or
precipitate of a still more basic sulphate, or of hydrated alumina
itself, Al_{2}(OH)_{6}, until we arrive at the salt
Al_{2}(SO_{4})_{2}(OH)_{2}, which is quite unstable on boiling;
Al_{2}(SO_{4})(OH)_{4} would be more unstable still. This behaviour may
be easily shown experimentally. We will dissolve some "cake alum" or
normal sulphate of alumina, Al_{2}(SO_{4})_{3}, in water, and boil some
of the solution. No deposit or precipitate is produced; the salt is
stable. To another portion of the solution we will add some caustic
soda, NaOH, in order to rob the normal sulphate of alumina of some of
its sulphuric acid. This makes the sulphate of alumina basic, and the
more basic, the more caustic soda is added, the sodium (Na) of the
caustic soda combining with the SO_{4} of the sulphate of alumina to
form sulphate of soda (Na_{2}SO_{4}), whilst the hydroxyl (OH) of the
caustic soda takes the position previously occupied by the SO_{4}. But
this increase of basicity also means decrease of stability, for on
boiling the solution, which now contains a basic sulphate of alumina, a
precipitate is formed, a result which also follows if more caustic soda
is added, production of still more basic salts or of hydrated alumina,
Al_{2}(OH)_{6}, taking place in either case.

_Mordanting or Fixing Acid (Phenolic) Colours._--But what has all this
to do with mordanting? is possibly now the inquiry. So much as this,
that only such unstable salts as I have just described, which decompose
and yield precipitates by the action on them of alkalis, heat, the
textile fibres themselves, or other agencies, are suitable to act as
true mordants. Hence, generally, the sources or root substances of the
best and most efficient mordants are the metals of high specific
appetite or valency. I think we have now got a clue to the principle of
mordants and also to the importance of a sound chemical knowledge in
dealing most effectively with them, and I may tell you that the man who
did most to elucidate the theory of mordanting is not a practical man in
the general sense of the term, but a man of the highest scientific
attainments and standing, namely, Professor Liechti, who, with his
colleague Professor Suida, did probably more than any other man to clear
up much that heretofore was cloudy in this region. We have seen that
with aluminium sulphate, basic salts are precipitated, _i.e._ salts with
such a predominance of appetite for acids, or such _quasi_-acids as
phenolic substances, that if such bodies were present they would combine
with the basic parts of those precipitated salts as soon as the latter
were formed, and all would be precipitated together as one complex
compound. Just such peculiar _quasi_-acid, or phenolic substances are
Alizarin, and most of the natural adjective dyestuffs, the colouring
principles of logwood, cochineal, Persian berries, etc. Hence these
substances will be combined and carried down with such precipitated
basic salts. The complex compounds thus produced are coloured substances
known as lakes. For example, if I take a solution containing basic
sulphate of alumina, prepared as I have already described, and add to
some Alizarin, and then heat the mixture, I shall get a red lake of
Alizarin and alumina precipitated. If I had taken sulphate of iron
instead of sulphate of alumina, and proceeded in a similar manner, and
added Alizarin, I should have obtained a dark purple lake. Now if you
imagine these reactions going on in a single fibre of a textile
material, you have grasped the theory and purpose of mordanting. The
textile fabric is drawn through the alumina solution to fill the pores
and tubes of the fabric; it is then passed through a weak alkaline bath
to basify or render basic the aluminium salt in the pores; and then it
is finally carried into the dye-bath and heated there, in order to
precipitate the colour lake in the fibre. The method usually employed to
mordant woollen fabrics consists in boiling them with weak solutions of
the metallic salts used as mordants, often with the addition of acid
salts, cream of tartar, and the like. A partial decomposition of the
metallic salts ensues, and it is induced by several conditions: (1) The
dilution of the liquid; (2) the heating of the solution; (3) the
presence of the fibre, which itself tends to cause the breaking up of
the metallic salts into less soluble basic ones. Thus it is not really
necessary to use basic aluminium sulphate for mordanting wool, since the
latter itself decomposes the normal or neutral sulphate of alumina on
heating, an insoluble basic sulphate being precipitated in the fibres of
the wool. (4) The presence of other added substances, as cream of
tartar, etc. The best alumina mordant is probably the acetate of
alumina ("red liquor"), and the best iron mordant, probably also the
acetate ("iron liquor") (see preceding lecture), because the acetic acid
is so harmless to the fibre, and is easily driven off on steaming, etc.
A further reason is that from the solution of acetate of iron or
alumina, basic acetates are very easily precipitated on heating, and are
thus readily deposited in the fibre.

_Mordanting and Fixing Basic Colours._--Now let us ask ourselves a very
important question. Suppose we have a colour or dyestuff, such as
Magenta, which is of a basic character, and not of an acid or phenolic
character like the colours Alizarin, Hæmatein (logwood), or carminic
acid (cochineal), and we wish to fix this basic dyestuff on the tissue.
Can we then use "red liquor" (acetate of alumina), acetate of iron,
copperas, etc.? The answer is, No; for such a process would be like
trying to combine base with base, instead of base with acid, in order to
form a salt. Combination, and so precipitation, would not take place; no
lake would be formed. We must seek for an acid or acid body to use as
mordant for our basic colour, and an acid or acid body that will form an
insoluble precipitate or colour-lake with the dyestuff. An acid much
used, and very valuable for this purpose, is tannic acid. The tannate of
rosaniline (colour principle of Magenta) is a tolerably insoluble lake,
which can be precipitated by Magenta from a solution of tannate of soda,
the Magenta being capable of displacing the soda. But tannic acid,
alone, does not form very fast lakes with Magenta and the other basic
dyestuffs, and so a means of rendering these lakes more insoluble is
needed. It is found that tannic acid and tartar emetic (a tartrate of
antimony and potash) yield a very insoluble compound, a tannate of
antimony. Perchloride of tin, in a similar manner, yields insoluble
tannate of tin with tannic acid. These insoluble compounds, however,
have sufficient acid-affinity left in the combined tannic acid to unite
also with the basic aniline colours, forming very fast or insoluble
colour lakes. This principle is extensively used in practice to fix
basic aniline colours, especially on cotton. We should first soak the
piece of cotton in a solution of tannic acid, and then pass it into a
solution, say, of tartar emetic, when the tannic acid will be firmly
fixed, as tannate of antimony, on the cotton. We then dip the mordanted
piece of cotton into the colour bath, containing, for instance, Magenta,
and it is dyed a fine red, composed of a tannate of antimony and
Magenta. You now see, no doubt, the necessity of sharply discriminating
between two classes of colouring matters, which we may term _colour
acids_ and _colour bases_ respectively. There are but few acids that act
like tannic acid in fixing basic aniline dyestuffs, but oleic acid and
other fatty acids are of the number. A curious question might now be
asked, namely: "Could the acid colour Alizarin, if fixed on cotton
cloth, combine with a basic aniline colour, _e.g._ Aniline Violet, and
act as a mordant for it, thus fixing it?" The answer is, "Certainly";
and thus an Alizarin Purple would be produced, whilst if Magenta were
used in place of Aniline Violet, an Alizarin Red of a crimson tone would
result.

_Chrome Mordanting of Wool and Fur._--In studying this subject I would
recommend a careful perusal of the chapter on "Mordants" in J.J.
Hummel's book, entitled _The Dyeing of Textile Fabrics_, and pages 337
to 340 of Bowman's work on _The Wool-Fibre_.

In the treatment of wool or fur with bichrome (potassium bichromate) we
start with an acid salt, a bichromate (K_{2}Cr_{2}O_{7}) and a strong
oxidising agent, and we finish with a basic substance, namely, oxide of
chromium, in the fibres of the wool or fur. If we desire to utilise the
whole of the chromic acid in our mordanting liquor, we must add to it
some sulphuric acid to set free the chromic acid from the potassium with
which it is combined. Bichromate of potash with sulphuric acid gives
sulphate of potash and chromic acid. The question of the proper
exhaustion of bichromate baths is an important economic one. Now we must
remember that this chromic acid (CrO_{3}) oxidises our wool or fur, and
must oxidise it before it can of itself act as a mordant by being
reduced in the process to hydrated chromic oxide, Cr_{2}O_{3} + 3
H_{2}O. [2 CrO_{3} (chromic acid) = Cr_{2}O_{3} (chromic oxide) + O_{3}
(oxygen).] It is this hydrated chromic oxide in the fibre that yields
with the Hæmatein of the logwood your logwood black dye. Mr. Jarmain
finds that it is not safe to use more than 3 per cent. (of the weight of
the wool) of bichromate; if 4 per cent. be used, the colour becomes
impaired, whilst if 12 per cent. be employed, the wool cannot be dyed at
all with logwood, the phenomenon known as "over-chroming" being the
result of such excessive treatment. I think there is no doubt, as
Professor Hummel says, that the colouring matter is oxidised and
destroyed in such over-chroming, but I also think that there can be no
doubt that the wool itself is also greatly injured and incapacitated for
taking up colour. Now the use of certain coal-tar black dyes in place of
logwood obviates this use of bichrome, and thus the heavy stress on the
fibre in mordanting with it. It also effects economy in avoiding the use
of bichrome, as well as of copper salts; but even thus, of course, other
problems have to be solved before it can be finally decided which is
best.



LECTURE IX

DYESTUFFS AND COLOURS


_Classification._--In classifying the different dyestuffs and colouring
matters it is, of course, necessary to consider first the properties of
those colouring matters generally, and secondly the particular reason
for making such classification. The scientific chemist, for example,
would classify them according to theoretical considerations, as members
of certain typical groups; the representative of medical science or
hygiene would naturally classify them as poisonous and non-poisonous
bodies; whilst the dyer will as naturally seek to arrange them according
to their behaviour when applied to textile fabrics. But this behaviour
on applying to textile fibres, if varied in character according to the
chemical nature of the colouring matter, as well as the chemical and
physical nature of the fabric--and it is so varied--will make such
classification, if it is to be thorough-going, not a very simple matter.
I may tell you that it is not a simple matter, and, moreover, the best
classification and arrangement is that one which depends both on the
action of the dyes on the fibres, and also on the intrinsic chemical
character of the dyestuffs themselves. Since the higher branches of
organic chemistry are involved in the consideration of the structure and
dispositions, and consequently more or less of the properties of these
dyes, you will readily comprehend that the thorough appreciation and use
of that highest and best method of classification, particularly in the
case of the coal-tar dyes, will be, more or less, a sealed book except
to the student of organic chemistry. But it may be asked, "How does that
highest and best method of classifying the dyestuffs affect the users,
the dyers, in their processes?" In reply, I would say, "I believe that
the dyer who so understands the chemical principles involved in the
processes he carries out, and in the best methods of classifying the
dyes as chemical substances, so as to be able to act independently of
the prescriptions and recipes given him by the dye manufacturers, and so
be master of his own position, will, _ceteris paribus_, be the most
economical and successful dyer." Many manufacturers of dyestuffs have
said the very same thing to me, but, independently of this, I know it,
and can prove it with the greatest ease. Let me now, by means of an
experiment or two, prove to you that at least some classification is
necessary to begin with. So different and varied are the substances used
as colouring matters by the dyer, both as regards their chemical and
physical properties, that they even act differently towards the same
fibre. I will take four pieces of cotton fabric; three of them are
simple white cotton, whilst the fourth cotton piece has had certain
metallic salts mixed with thickening substances like gum, printed on it
in the form of a pattern, which at present cannot readily be discerned.
We will now observe and note the different action on these pieces of
cotton--(i.) of a Turmeric bath, (ii.) a Magenta bath, and (iii.) a
madder or Alizarin bath. The Turmeric dyes the cotton a fast yellow, the
Magenta only stains the cotton crimson, and on washing with water alone,
almost every trace of colour is removed again; the madder, however,
stains the cotton with no presentable shade of colour at all, produces a
brownish-yellow stain, removed at once by a wash in water. But let us
take the printed piece of cotton and dye that in the Alizarin bath, and
then we shall discover the conditions for producing colours with such a
dyestuff as madder or Alizarin. Different coloured stripes are
produced, and the colours are conditioned by the kind of metallic salts
used. Evidently the way in which, the turmeric dyes the cotton is
different from that in which the madder dyes it. The first is a yellow
dyestuff, but it would be hard to assign any one shade or tint to
Alizarin as a dyestuff. In fact Alizarin (the principle of madder) is of
itself not a dye, but it forms with each of several metals a differently
coloured compound; and thus the metallic salt in the fabric is actually
converted into a coloured compound, and the fabric is dyed or printed.
The case is just the same with logwood black dyeing: without the
presence of iron ("copperas," etc.), sulphate of copper ("bluestone"),
or bichrome, you would get no black at all. We will now try similar
experiments with woollen fabrics, taking three simple pieces of flannel,
and also two pieces, the one having been first treated with a hot
solution of alum and cream of tartar, and the other with copperas or
sulphate of iron solution, and then washed. Turmeric dyes the first
yellow, like it did the cotton. Magenta, however, permanently dyes the
woollen as it did not the cotton. Alizarin only stains the untreated
woollen, whilst the piece treated with alumina is dyed red, and that
with iron, purple. If, however, the pieces treated with iron and alumina
had been dyed in the Magenta solution, only one colour would have been
the result, and that a Magenta-red in each case. Here we have, as proved
by our experiments, two distinct classes of colouring matters. The one
class comprises those which are of themselves the actual colour. The
colour is fully developed in them, and to dye a fabric they only require
fixing in their unchanged state upon that fabric. Such dyes are termed
_monogenetic_, because they can only generate or yield different shades
of but one colour. Indigo is such a dye, and so are Magenta, Aniline
Black, Aniline Violet, picric acid, Ultramarine Blue, and so on.
Ultramarine is not, it is true, confined to blue; you can get
Ultramarine Green, and even rose-coloured Ultramarine; but still, in
the hands of the dyer, each shade remains as it came from the
colour-maker, and so Ultramarine is a monogenetic colour. Monogenetic
means capable of generating one. Turning to the other class, which
comprises, as we have shown, Alizarin, and, besides, the colouring
principle of logwood (Hæmatein), Gallein, and Cochineal, etc., we have
bodies usually possessed of some colour, it is true, but such colour is
of no consequence, and, indeed, is of no use to dyers. These bodies
require a special treatment to bring out or develop the colours, for
there may be several that each is capable of yielding. We may consider
them as colour-giving principles, and so we term them _polygenetic_
colours. Polygenetic means capable of generating several or many. In the
various colours and dyes we have all phases, and the monogenetic shades
almost imperceptibly into the polygenetic. The mode of application of
the two classes of colours is, of course, in each case quite essentially
different, for in the case of the monogenetic class the idea is mainly
either to dye at once and directly upon, the unprepared fibre, or having
subjected the fabric to a previous preparation with a metallic or other
solution, to fix directly the one colour on that fabric, on which,
without such preparation, it would be loose. In the case of the
polygenetic class, the idea is necessarily twofold. The dyeing materials
are not colours, only colour generators. Hence in all cases the fabric
must be prepared with the twofold purpose--first, of using a metallic or
other agent, capable of yielding, with the dye material, the desired
colour; and secondly, of yielding it on the fibre in an insoluble and
permanent form. Now, though I have gone so far into this mode of
classification, because it does afford some information and light, yet I
can go no farther without getting into a territory that presupposes a
knowledge and acquaintance with the chemical structure of the colouring
matters as organic substances, which would be, at present, beyond us. I
shall now turn to another mode of classification, which, if not so
far-reaching as the other, is at least an exceedingly useful one. The
two methods may be combined to a considerable extent. By the latter plan
the colours may be conveniently divided into three groups: I.,
substantive colours; II., adjective colours; III., mineral and pigment
colours.

_Substantive Dyestuffs._--The substantive colours fix themselves readily
and directly on animal fibres and substances, but only a few amongst
them will dye vegetable fibres like cotton and linen directly. Almost
all substantive colours may, however, be fixed on cotton and linen by
first preparing or mordanting those vegetable fibres. Silk, wool, fur,
etc., act like fibre and mordant together, for they absorb and fix the
substantive colours firmly. In our experiments we saw that turmeric is
one of the few substantive colours fixing itself on both cotton and
wool, without any aid from a mordant or fixing agent. Magenta was also a
substantive colour, but Alizarin was certainly not one of this class.

_Adjective Dyestuffs._--Some of these substances are definitely coloured
bodies, but in some of them the colour is of no consequence or value,
and is quite different and distinct from the colour eventually formed on
the fibre, which colour only appears in conjunction with a special
mordant; but, again, some of them are not coloured, and would not colour
the fibre directly at all, only in conjunction with some mordant. All
the polygenetic colours are, of course, comprised in this class, for
example Alizarin and logwood (Hæmatein), whilst such monogenetic colours
as annatto and turmeric are substantive, for they will fix themselves
without a mordant on cotton and wool. The adjective colours can be
conveniently subdivided into--(_a_) those existing in nature, as logwood
(Hæmatein) and Cochineal; (_b_) those artificially formed from coal-tar
products, as Alizarin (madder), Gallein, etc.

_Mineral and Pigment Dyestuffs._--These colours are insoluble in water
and alcohol. They are either fixed on the fibre by mechanical means or
by precipitation. For example, you use blacklead or plumbago to colour
or darken your hats, and you work on this pigment colour by mechanical
means. I will show you by experiment how to fix a coloured insoluble
pigment in the fibre. I take a solution of acetate of lead (sugar of
lead), and to it I add some solution of bichrome (potassium bichromate).
Acetate of lead (soluble in water) with bichromate of potash (also
soluble in water) yields, on mixing the two, acetate of potash (soluble
in water), and chromate of lead, or chrome yellow (insoluble in water),
and which is consequently precipitated or deposited. Now suppose I boil
some of that chrome-yellow precipitate with lime-water, I convert that
chrome yellow into chrome orange. This, you see, takes place without any
reference to textile fibres. I will now work a piece of cotton in a lead
solution, so that the little tubes of the cotton fibre shall be filled
with it just as the larger glass tube or vessel was filled in the first
experiment. I next squeeze and wash the piece, so as to remove
extraneous solution of lead, just as if I had filled my glass tube by
roughly dipping it bodily into the lead solution, and then washed and
cleansed the outside of that tube. Then I place the fabric in a warm
solution of bichromate of potash (bichrome), when it becomes dyed a
chrome yellow, for just as chromate of lead is precipitated in the glass
tube, so it is now precipitated in the little tubes of the cotton fibre
(see Lecture I.). Let us see if we can now change our chrome yellow to
chrome orange, just as we did in the glass vessel by boiling in
lime-water. I place the yellow fabric in boiling lime-water, when it is
coloured or dyed orange. In each little tubular cotton fibre the same
change goes on as went on in the glass vessel, and as the tube or glass
vessel looks orange, so does the fabric, because the cotton fibres or
tubes are filled with the orange chromium compound. You see this is
quite a different process of pigment colouring from that of rubbing or
working a colour mechanically on to the fibre.

Let us now turn to the substantive colours (Group I.), and see if we can
further sub-divide this large group for the sake of convenience. We can
divide the group into two--(_a_) such colours as exist ready formed in
nature, and chiefly occur in plants, of which the following are the most
important: indigo, archil or orchil, safflower, turmeric, and annatto;
(_b_) the very large sub-group of the artificial or coal-tar colours. We
will briefly consider now the dyestuffs mentioned in Group (_a_).

_Natural Substantive Colours._--Indigo, one of the most valuable dyes,
is the product of a large number of plants, the most important being
different species of _indigofera_, which belong to the pea family. None
of the plants (of which _indigofera tinctoria_ is the chief) contain the
colouring matter in the free state, ready-made, so to say, but only as a
peculiar colourless compound called _indican_, first discovered by
Edward Schunck. When this body is treated with dilute mineral acids it
splits up into Indigo Blue and a kind of sugar. But so easily is this
change brought about that if the leaf of the plant be only bruised, the
decomposition ensues, and a blue mark is produced through separation of
the Indigo Blue. The possibility of dyeing with Indigo so readily and
easily is due to the fact that Indigo Blue absorbs hydrogen from bodies
that will yield it, and becomes, as we say, reduced to a body without
colour, called Indigo White, a body richer in hydrogen than Indigo Blue,
and a body that is soluble. If this white body (Indigo White) be exposed
to the air, the oxygen of the air undoes what the hydrogen did, and
oxidises that Indigo White to insoluble Indigo Blue. Textile fabrics
dipped in such reduced indigo solutions, and afterwards exposed to the
air, become blue through deposit in the fibres of the insoluble Indigo
Blue, and are so dyed. This is called the indigo-vat method. We can
reduce this indigo so as to prepare the indigo-vat by simply mixing
Indigo Blue, copperas (ferrous sulphate) solution, and milk of lime in a
closely-stoppered bottle with water, and letting the mixture stand. The
clear liquor only is used. A piece of cotton dipped in it, and exposed
to the air, quickly turns blue by absorbing oxygen, and is thus dyed.
The best proportions for the indigo-vat are, for cloth dyeing, 4000
parts of water, 40 of indigo, 60 to 80 of copperas crystals, and 50 to
100 of dry slaked lime. The usual plan is to put in the water first,
then add the indigo and copperas, which should be dissolved first, and
finally to add the milk of lime, stirring all the time. Artificial
indigo has been made from coal-tar products. The raw material is a
coal-tar naphtha called toluene or toluol, which is also the raw
material for saccharin, a sweetening agent made from coal-tar. This
artificial indigo is proving a formidable rival to the natural product.

Orchil paste, orchil extract, and cudbear are obtained by exposing the
plants (species of lichens) containing the colouring principle, called
_Orcin_, itself a colourless substance, to the joint action of ammonia
and air, when the oxygen of the air changes that orcin by oxidising it
into _Orcèin_, which is the true red colouring matter contained in the
preparations named. The lichens thus treated acquire gradually a deep
purple colour, and form the products called "cudbear." This dye works
best in a neutral bath, but it will do what not many dyes will, namely,
dye in either a slightly alkaline or slightly acid bath as well. Orchil
is not applicable in cotton dyeing. Being a substantive colour no
mordants are needed in dyeing silk and wool with it. The colour produced
on wool and silk is a bright magenta-red with bluish shade.

Litmus is also obtained from the same lichens as yield orchil. It is not
used in dyeing, and is a violet-blue colouring matter when neither acid
nor alkaline, but neutral as it is termed. It turns red with only a
trace of acid, and blue with the least trace of alkali, and so forms a
very delicate reagent when pieces of paper are soaked with it, and
dipped into the liquids to be tested.

Safflower: This vegetable dyeing material, for producing pink colours on
cotton without the aid of a mordant, consists of the petals of the
flower of _carthamus tinctorius_. It contains a principle termed
"Carthamin" or "carthamic acid," which can be separated by exhausting
safflower with cold acidulated water (sulphuric acid) to dissolve out a
yellow colouring matter which is useless. The residue after washing free
from acid is treated with a dilute solution of soda crystals, and the
liquid is then precipitated by an acid. A red precipitate is obtained,
which fixes itself directly on cotton thread immersed in the liquid, and
dyes it a delicate rose pink, which is, unfortunately, very fugitive.
Silk can be dyed like cotton. The colour is not fast against light.

Turmeric is the root portion of a plant called _curcuma tinctoria_, that
grows in Southern Asia. The principle forming the colouring matter is
"Curcumin." It is insoluble in cold water, not much soluble in hot, but
easily soluble in alcohol. From the latter solution it separates in
brilliant yellow crystals. Although the colour it yields is very
fugitive, the wool and silk dyers still use it for producing especially
olives, browns, and similar compound shades. It produces on cotton and
wool a bright yellow colour without the aid of any mordant. To show you
how easily dyeing with turmeric is effected, I will warm some powdered
turmeric root in a flask with alcohol, and add the extract to a vessel
of water warmed to about 140° F. (60° C.), and then dip a piece of
cotton in and stir it about, when it will soon be permanently dyed a
fine bright yellow. A piece of wool similarly worked in the bath is also
dyed. However, the unfortunate circumstance is that this colour is fast
neither to light nor alkalis. Contact with soap and water, even, turns
the yellow-dyed cotton, reddish-brown.

Annatto is a colouring principle obtained from the pulpy matter
enclosing the seeds of the fruit of a tree, the _Bixa orellana_, growing
in Central and Southern America. The red or orange colour it yields is
fugitive, and so its use is limited, being chiefly confined to silk
dyeing. The yellow compound it contains is called "Orellin," and it also
contains an orange compound called "Bixin," which is insoluble in water,
but readily soluble in alkalis and in alcohol with a deep yellow colour.
To dye cotton with it, a solution is made of the colour in a boiling
solution of carbonate of soda. The cotton is worked in the diluted
alkaline solution whilst hot. By passing the dyed cotton through water
acidulated with a little vitriol or alum, a redder tint is assumed. For
wool and silk, pale shades are dyed at 106° F. (50° C.) with the
addition of soap to the bath, dark shades at 200° to 212° F. (80° to
100° C.).



LECTURE X

DYESTUFFS AND COLOURS--_Continued_


_Artificial Substantive Dyestuffs._--You may remember that in the last
lecture we divided the colouring matters as follows: I. Substantive
colours, fixing themselves directly on animal fibres without a mordant,
only a few of them doing this, however, on vegetable fibres, like
cotton. We sub-divided them further as--(_a_) those occurring in nature,
and (_b_) those prepared artificially, and chiefly, but not entirely,
the coal-tar colouring matters. II. Adjective colours, fixing themselves
only in conjunction with a mordant or mordants on animal or vegetable
fibres, and including all the polygenetic colours. III. Mineral or
pigment colours. I described experiments to illustrate what we mean by
monogenetic and polygenetic colours, and indicating that the monogenetic
colours are mainly included in the group of substantive colours, whilst
the polygenetic colours are mainly included in the adjective colours.
But I described also an illustration of Group III., the mineral or
pigment colours, by which we may argue that chromate of lead is a
polygenetic mineral colour, for, according to the treatment, we were
able to obtain either chrome yellow (neutral lead chromate) or chrome
orange (basic lead chromate). I also said there was a kind of borderland
whichever mode of classification be adopted. Thus, for example, there
are colours that are fixed on the fibre either directly like indigo, and
so are substantive, or they may be, and generally are, applied with a
mordant like the adjective and polygenetic colours; examples of these
are Coerulein, Alizarin Blue, and a few more. We have now before us a
vast territory, namely, that of the _b_ group of substantive colours,
or, the largest proportion, indeed almost all of those prepared from
coal-tar sources; Alizarin, also prepared from coal-tar, belongs to the
adjective colours. With regard to the source of these coal-tar colours,
the word "coal-tar," I was going to say, speaks volumes, for the
destructive and dry distillation of coal in gas retorts at the highest
temperatures to yield illuminating gas, also yields us tar. But, coal
distilled at lower temperatures, as well as shale, as in Scotland, will
yield tar, but tar of another kind, from which colour-generating
substances cannot be obtained practically, but instead, paraffin oil and
paraffin wax for making candles, etc. Coal-tar contains a very large
number of different substances, but only a few of them can be extracted
profitably for colour-making. All the useful sources of colours and dyes
from coal-tar are simply compounds of carbon and hydrogen--hydrocarbons,
as they are called, with the exception of one, namely, phenol, or
carbolic acid. I am not speaking here of those coal-tar constituents
useful for making dyes, but of those actually extracted from coal-tar
for that purpose, _i.e._ extracted to profit. For example, aniline is
contained in coal-tar, but if we depended on the aniline contained ready
made in coal-tar for our aniline dyes, the prices of these dyes would
place them beyond our reach, would place them amongst diamonds and
precious stones in rarity and cost, so difficult is it to extract the
small quantity of aniline from coal-tar. The valuable constituents
actually extracted are then these: benzene, toluene, xylene,
naphthalene, anthracene, and phenol or carbolic acid. One ton of
Lancashire coal, when distilled in gas retorts, yields about 12 gallons
of coal-tar. Let us now learn what those 12 gallons of tar will give us
in the shape of hydrocarbons and carbolic acid, mentioned as extracted
profitably from tar. This is shown very clearly in the following table
(Table A).

The 12 gallons of tar yield 1-1/10 lb. of benzene, 9/10 lb. of toluene,
1-1/2 lb. of carbolic acid, between 1/10 and 2/10 lb. of xylene, 6-1/2
lb. of naphthalene, and 1/2 lb. of anthracene, whilst the quantity of
pitch left behind is 69-1/2 lb. But our table shows us more; it
indicates to us what the steps are from each raw material to each
colouring matter, as well as showing us each colouring matter. We see
here that our benzene yields us an equal weight of aniline, and the
toluene (9/10 lb.) about 3/4 lb. of toluidine, the mixture giving, on
oxidation, between 1/2 and 3/4 lb of Magenta. From carbolic acid are
obtained both Aurin and picric acid, and here is the actual quantity of
Aurin obtainable (1-1/4 lb.). From naphthalene, either naphthylamine (a
body like aniline) or naphthol (resembling phenol) may be prepared. The
amounts obtainable you see in the table. There are two varieties of
naphthol, called alpha- and beta-naphthol, but only one phenol, namely,
carbolic acid. Naphthol Yellow is of course a naphthol colour, whilst
Vermilline Scarlet is a dye containing both naphthylamine and naphthol.
You see the quantities of these dyes, namely 7 lb. of Scarlet and 9-1/2
lb. of the Naphthol Yellow. The amount of pure anthracene obtained is
1/2 lb. This pure anthracene exhibits the phenomenon of fluorescence,
that is, it not only looks white, but when the light falls on it, it
seems to reflect a delicate violet or blue light. Our table shows us
that from the 12 gallons of tar from 1 ton of coal we may gain 2-1/4 lb.
of 20 per cent. Alizarin paste. Chemically pure Alizarin crystallises in
bright-red needles; it is the colouring principle of madder, and also of
Alizarin paste. But the most wonderful thing about substantive coal-tar
colours is their immense tinctorial power, _i.e._ the very little
quantity of each required compared with the immense superficies of cloth
it will dye to a full shade.

TABLE A.[2]

-------------------------------------------------------------------------------
                     TWELVE GALLONS OF GAS-TAR
         (AVERAGE OF MANCHESTER AND SALFORD TAR) YIELD:--
---------+---------+------+----------+----+--------------+---+---+--------+----
 Benzene.| Toluene.|  P   |Solvent   | H N| Naphthalene. | C | H |   A    | P
         |         |  h   |Naphtha   | e a|              | r | e |   n    | i
         |         |  e   |for       | a p|              | e | a |   t    | t
         |         |  n   |India     | v h|              | o | v |   h    | c
         |         |  o   |rubber,   | y t|              | s | y |   r    | h
         |         |  l   |containing|   h|              | o |   |   a    | .
         |         |  .   |the three |   a|              | t | O |   c    |
         |         |      |Xylenes.  |   .|              | e | i |   e    |
         |         |      |          |    |              | . | l |   n    |
         |         |      |          |    |              |   | . |   e.   |
---------+----------------+----------+----+--------------+---+---+-------------
1·10 lb.=|0·90 lb.=|1·5   |2·44 lb., |2·40|6·30 lb. =    |17 |14 |0·46 lb.|69·6
1·10 lb. |0·77 lb. |lb.   |yielding  |lb. |5·25 lb. of   |lb.|lb.|= 2·25  | lb.
of       | of      |= 1·2 |0·12 lb.  |    |alpha-        |   |   | lb. of |
Aniline  |Toluidine|lb. of|of Xylene |    |Naphthylamine |   |   |Alizarin|
         |         |Aurin.|= 0·07 lb.|    |= 7·11 lb. of |   |   | (20%). |
         |         |      |of        |    |Vermilline    |   |   |        |
\________________/ |      |Xylidine  |    |Scarlet       |   |   |        |
  = 0·623 lb of    |      |          |    |RRR; or 4·75  |   |   |        |
      Magenta.     |      |          |    |lb. of        |   |   |        |
         |         |      |          |    |alpha-        |   |   |        |
or 1·10  |         |      |          |    |or beta-      |   |   |        |
lb. of   |         |      |          |    |Naphthol      |   |   |        |
Aniline  |         |      |          |    |= 9·50 lb. of |   |   |        |
yields   |         |      |          |    |Naphthol      |   |   |        |
1·23 lb. |         |      |          |    |Yellow        |   |   |        |
of Methyl|         |      |          |    |              |   |   |        |
Violet.  |         |      |          |    |              |   |   |        |
---------+---------+------+----------+----+--------------+---+---+--------+----

[Footnote 2: This table was compiled by Mr. Ivan Levinstein, of
Manchester.]

The next table (see Table B) shows you the dyeing power of the colouring
matters derived from 1 ton of Lancashire coal, which will astonish any
thoughtful mind, for the Magenta will dye 500 yards of flannel, the
Aurin 120 yards, the Vermilline Scarlet 2560 yards, and the Alizarin 255
yards (Turkey-red cotton cloth).

The next table (Table C) shows the latent dyeing power resident, so to
speak, in 1 lb. of coal.

By a very simple experiment a little of a very fine violet dye can be
made from mere traces of the materials. One of the raw materials for
preparing this violet dye is a substance with a long name, which itself
was prepared from aniline. This substance is
tetramethyldiamidobenzophenone, and a little bit of it is placed in a
small glass test-tube, just moistened with a couple of drops of another
aniline derivative called dimethylaniline, and then two drops of a
fuming liquid, trichloride of phosphorus, added. On simply warming this
mixture, the violet dyestuff is produced in about a minute. Two drops of
the mixture will colour a large cylinder of water a beautiful violet.
The remainder (perhaps two drops more) will dye a skein of silk a bright
full shade of violet. Here, then, is a magnificent example of enormous
tinctorial power. I must now draw the rein, or I shall simply transport
you through a perfect wonderland of magic, bright colours and apparent
chemical conjuring, without, however, an adequate return of solid
instruction that you can carry usefully with you into every-day life and
practice.

TABLE B.[3]

-------------------------------------------------------------------------------
       DYEING POWERS OF COLOURS FROM 1 TON OF LANCASHIRE COAL.
------------+------------+------------+-------------+-------------+------------
0·623 lb. of|1·34 lb. of |9.5 lb. of  |7·11 lb. of  |1·2 lb. of   |2·25 lb. of
Magenta will|Methyl      |Naphthol    |Vermilline   |Aurin will   |Alizarin
dye 500     |Violet will |Yellow will |will dye 2560|dye  120     |(20%) will
yards of    |dye 1000    |dye 3800    |yards of     |yards of     |dye 255
flannel, 27 |yards of    |yards of    |flannel, 27  |flannel, 27  |yards of
inches wide,|flannel, 27 |flannel, 27 |inches wide, |inches wide, |Printers'
a full      |inches wide,|inches wide,|a full       |a full       |cloth a full
shade.      |a full      |a full      |scarlet.     |orange.      |Turkey red.
            |violet.     |yellow.     |             |             |
------------+------------+------------+-------------+-------------+------------

TABLE C.[3]
-------------------------------------------------------------------------------
       DYEING POWERS OF COLOURS FROM 1 LB. OF LANCASHIRE COAL.
------------+------------+------------+-------------+-------------+------------
                Methyl   | Naphthol      Vermilline |    Aurin    |  Alizarin
  Magenta  or   Violet.  |  Yellow.  or   Scarlet.  |  (Orange).  |(Turkey Red)
------------+------------+------------+-------------+-------------+------------
8 × 27      |24 × 27     |61 × 27     |41 × 27      |1·93 × 27    |4 × 27
inches of   |inches of   |inches of   |inches of    |inches of    |inches of
flannel.    |flannel.    |flannel.    |flannel.     |flannel.     |Printers'
            |            |            |             |             |cloth.
------------+------------+------------+-------------+-------------+------------

[Footnote 3: These tables were compiled by Mr. Ivan Levinstein, of
Manchester.]

Before we go another step, I must ask and answer, therefore, a few
questions. Can we not get some little insight into the structure and
general mode of developing the leading coal-tar colours which serve as
types of whole series? I will try what can be done with the little
knowledge of chemistry we have so far accumulated. In our earlier
lectures we have learnt that water is a compound of hydrogen and oxygen,
and in its compound atom or molecule we have two atoms of hydrogen
combined with one of oxygen, symbolised as H_{2}O. We also learnt that
ammonia, or spirits of hartshorn, is a compound of hydrogen with
nitrogen, three atoms of hydrogen being combined with one of nitrogen,
thus, NH_{3}. An example of a hydrocarbon or compound of carbon and
hydrogen, is marsh gas (methane) or firedamp, CH_{4}. Nitric acid, or
_aqua fortis_, is a compound of nitrogen, oxygen, and hydrogen, one atom
of the first to three of the second and one of the third--NO_{3}H. But
this nitric acid question forces me on to a further statement, namely,
we have in this formula or symbol, NO_{3}H, a twofold idea--first, that
of the compound as a whole, an acid; and secondly, that it is formed
from a substance without acid properties by the addition of water,
H_{2}O, or, if we like, HOH. This substance contains the root or radical
of the nitric acid, and is NO_{2}, which has the power of replacing one
of the hydrogen atoms, or H, of water, and so we get, instead of HOH,
NO_{2}OH, which is nitric acid. This is chemical replacement, and on
such replacement depends our powers of building up not only colours, but
many other useful and ornamental chemical structures. You have all heard
the old-fashioned statement that "Nature abhors a vacuum." We had a very
practical example of this when in our first lecture on water I brought
an electric spark in contact with a mixture of free oxygen and hydrogen
in a glass bulb. These gases at once united, three volumes of them
condensing to two volumes, and these again to a minute particle of
liquid water. A vacuum was left in that delicate glass bulb whilst the
pressure of the atmosphere was crushing with a force of 15 lb. on the
square inch on the outside of the bulb, and thus a violent crash was the
result of Nature's abhorrence. There is such a kind of thing, though,
and of a more subtle sort, which we might term a chemical vacuum, and it
is the result of what we call chemical valency, which again might be
defined as the specific chemical appetite of each substance.

Let us now take the case of the production of an aniline colour, and let
us try to discover what aniline is, and how formed. I pointed to benzene
or benzol in the table as a hydrocarbon, C_{6}H_{6}, which forms a
principal colour-producing constituent of coal-tar. If you desire to
produce chemical appetite in benzene, you must rob it of some of its
hydrogen. Thus C_{6}H_{5} is a group that would exist only for a moment,
since it has a great appetite for H, and we may say this appetite would
go the length of at once absorbing either one atom of H (hydrogen) or of
some similar substance or group having a similar appetite. Suppose, now,
I place some benzene, C_{6}H_{6}, in a flask, and add some nitric acid,
which, as we said, is NO_{2}OH. On warming the mixture we may say a
tendency springs up in that OH of the nitric acid to effect union with
an H of the C_{6}H_{6} (benzene) to form HOH (water), when an appetite
is at once left to the remainder, C_{6}H_{5}--on the one hand, and the
NO_{2}--on the other, satisfied by immediate union of these residues to
form a substance C_{6}H_{6}NO_{2}, nitro-benzene or "essence of
mirbane," smelling like bitter almonds. This is the first step in the
formation of aniline.

I think I have told you that if we treat zinc scraps with water and
vitriol, or water with potassium, we can rob that water of its oxygen
and set free the hydrogen. It is, however, a singular fact that if we
liberate a quantity of fresh hydrogen amongst our nitrobenzene
C_{6}H_{5}NO_{2}, that hydrogen tends to combine, or evinces an
ungovernable appetite for the O_{2} of that NO_{2} group, the tendency
being again to form water H_{2}O. This, of course, leaves the residual
C_{6}H_{5}N: group with an appetite, and only the excess of hydrogen
present to satisfy it. Accordingly hydrogen is taken up, and we get
C_{6}H_{5}NH_{2} formed, which is aniline. I told you that ammonia is
NH_{3}, and now in aniline we find an ammonia derivative, one atom of
hydrogen (H) being replaced by the group C_{6}H_{5}. I will now describe
the method of preparation of a small quantity of aniline, in order to
illustrate what I have tried to explain in theory. Benzene from coal-tar
is warmed with nitric acid in a flask. A strong action sets in, and on
adding water, the nitrobenzene settles down as a heavy oil, and the acid
water can be decanted off. After washing by decantation with water once
or twice, and shaking with some powdered marble to neutralise excess of
acid, the nitrobenzene is brought into contact with fresh hydrogen gas
by placing amongst it, instead of zinc, some tin, and instead of
vitriol, some hydrochloric acid (spirits of salt). To show you that
aniline is formed, I will now produce a violet colour with it, which
only aniline will give. This violet colour is produced by adding a very
small quantity of the aniline, together with some bleaching powder, to a
mixture of chalk and water, the chalk being added for the purpose of
destroying acidity. This aniline, C_{6}H_{5}NH_{2}, is a base, and forms
the foundation of all the so-called basic aniline colours. If I have
made myself clear so far, I shall be contented. It only remains to be
said that for making Magenta, pure aniline will not do, what is used
being a mixture of aniline, with an aniline a step higher, prepared from
toluene. If I were to give you the formula of Magenta you would be
astonished at its complexity and size, but I think now you will see that
it is really built up of aniline derivatives. Methyl Violet is a colour
we have already referred to, and its chemical structure is still more
complex, but it also is built up of aniline materials, and so is a basic
aniline colour. Now it is possible for the colour-maker to prepare a
very fine green dye from this beautiful violet (Methyl Violet). In fact
he may convert the violet into the green colour by heating the first
under pressure with a gas called methyl chloride (CH_{3}Cl). Methyl
Violet is constructed of aniline or substituted aniline groups; the
addition of CH_{3}Cl, then, gives us the Methyl Green. But one of the
misfortunes of Methyl Green is that if the fabric dyed with it be boiled
with water, at that temperature (212° F.) the colour is decomposed and
injured, for some of the methyl chloride in the compound is driven off.
In fact, by stronger heating we may drive off all the methyl chloride
and get the original Methyl Violet back again.

But we have coal-tar colours which are not basic, but rather of the
nature of acid,--a better term would be _phenolic_, or of the nature of
phenol or carbolic acid. Let us see what phenol or carbolic acid is. We
saw that water may be formulated HOH, and that benzene is C_{6}H_{6}.
Well, carbolic acid or phenol is a derivative of water, or a derivative
of benzene, just as you like, and it is formulated C_{6}H_{5}OH. You can
easily prove this by dropping carbolic acid or phenol down a red-hot
tube filled with iron-borings. The oxygen is taken up by the iron to
give oxide of iron, and benzene is obtained, thus: C_{6}H_{5}OH gives O
and C_{6}H_{6}. But there is another hydrocarbon called naphthalene,
C_{10}H_{8}, and this forms not one, but two phenols. As the name of the
hydrocarbon is naphthalene, however, we call these compounds naphthols,
and one is distinguished as alpha- the other as beta-naphthol, both of
them having the formula C_{10}H_{7}OH. But now with respect to the
colours. If we treat phenol with nitric acid under proper conditions, we
get a yellow dye called picric acid, which is trinitro-phenol
C_{6}H_{2}(NO_{2})_{3}OH; you see this is no aniline dye; it is not a
basic colour, for it would saturate, _i.e._ destroy the basicity of
bases. Again, by oxidising phenol with oxalic acid and vitriol, we get a
colour dyeing silk orange, namely, Aurin, HO.C[C_{6}H_{4}(OH)]_{3}. This
is also an acid or phenolic dye, as a glance at its formula will show
you. Its compound atom bristles, so to say, with phenol-residues, as
some of the aniline dyes do with aniline residue-groups.

We come now to a peculiar but immensely important group of colours known
as the azo-dyes, and these can be basic or acid, or of mixed kind. Just
suppose two ammonia groups, NH_{3} and NH_{3}. If we rob those nitrogen
atoms of their hydrogen atoms, we should leave two unsatisfied nitrogen
atoms, atoms with an exceedingly keen appetite represented in terms of
hydrogen atoms as N*** and N***. We might suppose a group, though of two N
atoms partially satisfied by partial union with each other, thus--N:N--.
Now this group forms the nucleus of the azo-colours, and if we satisfy a
nitrogen at one side with an aniline, and at the other with a phenol, or
at both ends with anilines, and so on, we get azo-dyes produced. The
number of coal-tar colours is thus very great, and the variety also.

_Adjective Colours._--As regards the artificial coal-tar adjective
dyestuffs, the principal are Alizarin and Purpurin. These are now almost
entirely prepared from coal-tar anthracene, and madder and garancine are
almost things of the past. Vegetable adjective colours are Brazil wood,
containing the dye-generating principle Brasilin, logwood, containing
Hæmatein, and santal-wood, camwood, and barwood, containing Santalin.
Animal adjective colours are cochineal and lac dye. Then of wood colours
we have further: quercitron, Persian berries, fustic and the tannins or
tannic acids, comprising extracts, barks, fruits, and gallnuts, with
also leaves and twigs, as with sumac. All these colours dye only with
mordants, mostly forming with certain metallic oxides or basic salts,
brightly-coloured compounds on the tissues to which they are applied.



LECTURE XI

DYEING OF WOOL AND FUR; AND OPTICAL PROPERTIES OF COLOURS


You have no doubt a tolerably vivid recollection of the illustrations
given in Lecture I., showing the structure of the fibre of wool and fur.
We saw that the wool fibre, of which fur might be considered a coarser
quality, possesses a peculiar, complex, scaly structure, the joints
reminding one of the appearance of plants of the _Equisetum_ family,
whilst the scaled structure resembles that of the skin of the serpent.
Now you may easily understand that a structure like this, if it is to be
completely and uniformly permeated by a dye liquor or any other aqueous
solution, must have those scales not only well opened, but well
cleansed, because if choked with greasy or other foreign matter
impervious to or resisting water, there can be no chance of the
mordanting or dye liquids penetrating uniformly; the resulting dye must
be of a patchy nature. All wool, in its natural state, contains a
certain amount of a peculiar compound almost like a potash soap, a kind
of soft soap, but it also contains besides, a kind of fatty substance
united with lime, and of a more insoluble nature than the first. This
natural greasy matter is termed "yolk" or "suint"; and it ought never to
be thrown away, as it sometimes is by the wool-scourers in this country,
for it contains a substance resembling a fat named _cholesterin_ or
_cholesterol_, which is of great therapeutical value. Water alone will
wash out a considerable amount of this greasy matter, forming a kind of
lather with it, but not all. As is almost invariably the case, after
death, the matters and secretions which in life favour the growth and
development of the parts, then commence to do the opposite. It is as if
the timepiece not merely comes to a standstill, but commences to run
backwards. This natural grease, if it be allowed to stand in contact
with the wool for some time after shearing, instead of nourishing and
preserving the fibres as it does on the living animal, commences to
ferment, and injures them by making them hard and brittle. We see, then,
the importance of "scouring" wool for the removal of "yolk," as it is
called, dirt, oil, etc. If this important operation were omitted, or
incompletely carried out, each fibre would be more or less covered or
varnished with greasy matter, resisting the absorption and fixing of
mordant and dye. As scouring agents, ammonia, carbonate of ammonia,
carbonate of soda completely free from caustic, and potash or soda
soaps, especially palm-oil soaps, which need not be made with bleached
palm oil, but which must be quite free from free alkali, may be used. In
making these palm-oil soaps it is better to err on the side of a little
excess of free oil or fat, but if more than 1 per cent. of free fat be
present, lathering qualities are then interfered with. Oleic acid soaps
are excellent, but are rather expensive for wool; they are generally
used for silks. Either as a skin soap or a soap for scouring wools, I
should prefer one containing about 1/2 per cent. of free fatty matter,
of course perfectly equally distributed, and not due to irregular
saponification. On the average the soap solution for scouring wool may
contain about 6-1/2 oz. of soap to the gallon of water. In order to
increase the cleansing powers of the soap solution, some ammonia may be
added to it. However, if soap is used for wool-scouring, one thing must
be borne in mind, namely, that the water used must not be hard, for if
insoluble lime and magnesia soaps are formed and precipitated on the
fibre, the scouring will have removed one evil, but replaced it by
another. The principal scouring material used is one of the various
forms of commercial carbonate of soda, either alone or in conjunction
with soap. Whatever be the form or name under which the carbonate of
soda is sold, it must be free from hydrate of soda, _i.e._ caustic soda,
or, as it is also termed, "causticity." By using this carbonate of soda
you may dispense with soap, and so be able, even with a hard or
calcareous water, to do your wool-scouring without anything like the ill
effects that follow the use of soap and calcareous water. The carbonate
of soda solutions ought not to exceed the specific gravity of 1° to 2°
Twaddell (1-1/2 to 3 oz. avoird. per gallon of water). The safest plan
is to work with as considerable a degree of dilution and as low a
temperature as are consistent with fetching the dirt and grease off. The
scouring of loose wool, as we may now readily discern, divides itself
into three stages: 1st, the stage in which those "yolk" or "suint"
constituents soluble in water, are removed by steeping and washing in
water. This operation is generally carried out by the wool-grower
himself, for he desires to sell wool, and not wool plus "yolk" or
"suint," and thus he saves himself considerable cost in transport. The
water used in this process should not be at a higher temperature than
113° F., and the apparatus ought to be provided with an agitator; 2nd,
the cleansing or scouring proper, with a weak alkaline solution; 3rd,
the rinsing or final washing in water.

Thus far we have proceeded along the same lines as the woollen
manufacturer, but now we must deviate from that course, for he requires
softness and delicacy for special purposes, for spinning and weaving,
etc.; but the felt manufacturer, and especially the manufacturer of felt
for felt hats, requires to sacrifice some of this softness and delicacy
in favour of greater felting powers, which can only be obtained by
raising the scales of the fibres by means of a suitable process, such
as treatment with acids. This process is one which is by no means
unfavourable to the dyeing capacities of the wool; on the whole it is
decidedly favourable.

So far everything in the treatment of the wool has been perfectly
favourable for the subsequent operations of the felt-hat dyer, but now I
come to a process which I consider I should be perfectly unwarranted in
passing over before proceeding to the dyeing processes. In fact, were it
not for this "proofing process" (see Lecture VII.) the dyeing of felt
hats would be as simple and easy of attainment as the ordinary dyeing of
whole-wool fabrics. Instead of this, however, I consider the hat
manufacturer, as regards his dyeing processes as applied to the stiffer
classes of felt hats, has difficulties to contend with fully comparable
with those which present themselves to the dyer of mixed cotton and
woollen or Bradford goods. You have heard that the purpose of the
wool-scourer is to remove the dirt, grease, and so-called yolk, filling
the pores and varnishing the fibres. Now the effect of the work of the
felt or felt-hat proofer is to undo nearly all this for the sake of
rendering the felt waterproof and stiff. The material used, also, is
even more impervious and resisting to the action of aqueous solutions of
dyes and mordants than the raw wool would be. In short, it is impossible
to mordant and to dye shellac by any process that will dye wool. To give
you an idea of what it is necessary to do in order to colour or dye
shellac, take the case of coloured sealing-wax, which is mainly composed
of shellac, four parts, and Venice turpentine, one part. To make red
sealing-wax this mixture is melted, and three parts of vermilion, an
insoluble metallic pigment, are stirred in. If black sealing-wax is
required, lamp-black or ivory-black is stirred in. The fused material is
then cast in moulds, from which the sticks are removed on cooling. That
is how shellac may be coloured as sealing-wax, but it is a totally
different method from that by which wool is dyed. The difficulty then is
this--in proofing, your hat-forms are rendered impervious to the dye
solutions of your dye-baths, all except a thin superficial layer, which
then has to be rubbed down, polished, and finished. Thus in a short
time, since the bulk of that superficially dyed wool or fur on the top
of every hat is but small, and has been much reduced by polishing and
rubbing, you soon hear of an appearance of bareness--I was going to say
threadbareness--making itself manifest. This is simply because the
colour or dye only penetrates a very little way down into the substance
of the felt, until, in fact, it meets the proofing, which, being as it
ought to be, a waterproofing, cannot be dyed. It cannot be dyed either
by English or German methods; neither logwood black nor coal-tar blacks
can make any really good impression on it. Cases have often been
described to me illustrating the difficulty in preventing hats which
have been dyed black with logwood, and which are at first a handsome
deep black, becoming rather too soon of a rusty or brownish shade. Now
my belief is that two causes may be found for this deterioration. One is
the unscientific method adopted in many works of using the same bath
practically for about a month together without complete renewal. During
this time a large quantity of a muddy precipitate accumulates, rich in
hydrated oxide of iron or basic iron salts of an insoluble kind. This
mud amounts to no less than 25 per cent. of the weight of the copperas
used. From time to time carbonate of ammonia is added to the bath, as it
is said to throw up "dirt." The stuff or "dirt," chiefly an ochre-like
mass stained black with the dye, and rich in iron and carbonate of iron,
is skimmed off, and fresh verdigris and copperas added with another lot
of hat-forms. No doubt on adding fresh copperas further precipitation of
iron will take place, and so this ochre-like precipitate will
accumulate, and will eventually come upon the hats like a kind of thin
black mud. Now the effect of this will be that the dyestuff, partly in
the fibre as a proper dye, and not a little on the fibre as if
"smudged" on or painted on, will, on exposure to the weather, moisture,
air, and so on, gradually oxidise, the great preponderance of iron on
the fibre changing to a kind of iron-rust, corroding the fibres in the
process, and thus at once accounting for the change to the ugly brownish
shade, and to the rubbing off and rapid wearing away of the already too
thin superficial coating of dyed felt fibre. In the final spells of
dyeing in the dye-beck already referred to, tolerably thick with black
precipitate or mud, the application of black to the hat-forms begins, I
fear, to assume at length a too close analogy to another blacking
process closely associated with a pair of brushes and the time-honoured
name of Day & Martin. With that logwood black fibre, anyone could argue
as to a considerable proportion of the dye rubbing, wearing, or washing
off. Thus, then, we have the second cause of the deterioration of the
black, for the colour could not go into the fibre, and so it was chiefly
laid or plastered on. You can also see that a logwood black hat dyer may
well make the boast, and with considerable appearance of truth, that for
the purposes of the English hat manufacturers, logwood black dyeing is
the most appropriate, _i.e._ for the dyeing of highly proofed and stiff
goods, but as to the permanent character of the black colour on those
stiff hats, there you have quite another question. I firmly believe that
in order to get the best results either with logwood black or "aniline
blacks," it is absolutely necessary to have in possession a more
scientific and manageable process of proofing. Such a process is that
invented by F.W. Cheetham (see Lecture VII. p. 66).

In the dyeing of wool and felt with coal-tar colours, it is in many
cases sufficient to add the solution of the colouring matters to the
cold or tepid water of the dye-bath, and, after introducing the woollen
material, to raise the temperature of the bath. The bath is generally
heated to the boiling-point, and kept there for some time. A large
number of these coal-tar colours show a tendency of going so rapidly
and greedily on to the fibre that it is necessary to find means to
restrain them. This is done by adding a certain amount of Glauber's
salts (sulphate of soda), in the solution of which coal-tar colours are
not so soluble as in water alone, and so go more slowly, deliberately,
and thus evenly upon the fibre. It is usually also best to dye in a bath
slightly acid with sulphuric acid, or to add some bisulphate of soda.
There is another point that needs good heed taking to, namely, in using
different coal-tar colours to produce some mixed effect, or give some
special shade, the colours to be so mixed must possess compatibility
under like circumstances. For example, if you want a violet of a very
blue shade, and you take Methyl Violet and dissolve it in water and then
add Aniline Blue also in solution, you find that precipitation of the
colour takes place in flocks. A colouring matter which requires, as some
do, to be applied in an acid bath, ought not to be applied
simultaneously with one that dyes best in a neutral bath. Numerous
descriptions of methods of using coal-tar dyestuffs in hat-dyeing are
available in different volumes of the _Journal of the Society of
Chemical Industry_, and also tables for the detection of such dyestuffs
on the fibre.

Now I will mention a process for dyeing felt a deep dead black with a
coal-tar black dye which alone would not give a deep pure black, but one
with a bluish-purple shade. To neutralise this purple effect, a small
quantity of a yellow dyestuff and a trifle of indigotin are added. A
deep black is thus produced, faster to light than logwood black it is
stated, and one that goes on the fibre with the greatest ease. But I
have referred to the use of small quantities of differently coloured
dyes for the purpose of neutralising or destroying certain shades in the
predominating colour. Now I am conscious that this matter is one that is
wrapped in complete mystery, and far from the true ken of many of our
dyers; but the rational treatment of such questions possesses such vast
advantages, and pre-supposes a certain knowledge of the theory of
colour, of application and advantage so equally important, that I am
persuaded I should not close this course wisely without saying a few
words on that subject, namely, the optical properties of colours.

Colour is merely an impression produced upon the retina, and therefore
on the brain, by various surfaces or media when light falls upon them or
passes through them. Remove the light, and colour ceases to exist. The
colour of a substance does not depend so much on the chemical character
of that substance, but rather and more directly upon the physical
condition of the surface or medium upon which the light falls or through
which it passes. I can illustrate this easily. For example, there is a
bright-red paint known as Crooke's heat-indicating paint. If a piece of
iron coated with this paint be heated to about 150° F., the paint at
once turns chocolate brown, but it is the same chemical substance, for
on cooling we get the colour back again, and this can be repeated any
number of times. Thus we see that it is the peculiar physical structure
of bodies which appear coloured that has a certain effect upon the
light, and hence it must be from the light itself that colour really
emanates. Originally all colour proceeds from the source of light,
though it seems to come to the eye from the apparently coloured objects.
But without some elucidation this statement would appear as an enigma,
since it might be urged that the light of the sun as well as that of
artificial light is white, and not coloured. I hope, however, to show
you that that light is white, because it is so much coloured, so
variously and evenly coloured, though I admit the term "coloured" here
is used in a special sense. White light contains and is made up of all
the differently coloured rainbow rays, which are continually vibrating,
and whose wave-lengths and number of vibrations distinguish them from
each other. We will take some white light from an electric lantern and
throw it on a screen. In a prism of glass we have a simple instrument
for unravelling those rays, and instead of letting them all fall on the
same spot and illumine it with a white light, it causes them to fall
side by side; in fact they all fall apart, and the prism has actually
analysed that light. We get now a coloured band, similar to that of the
rainbow, and this band is called the spectrum (see Fig. 16). If we could
now run all these coloured rays together again, we should simply
reproduce white light. We can do this by catching the coloured band in
another prism, when the light now emerging will be found to be white.
Every part of that spectrum consists of homogeneous light, _i.e._ light
that cannot be further split up. The way in which the white light is so
unravelled by the prism is this: As the light passes through the prism
its different component coloured rays are variously deflected from their
normal course, so that on emerging we have each of these coloured rays
travelling in its own direction, vibrating in its own plane. It is well
to remember that the bending off, or deflection, or refraction, is
towards the thick end of the prism always, and that those of the
coloured rays in that analysed band, the spectrum, most bent away from
the original line of direction of the white light striking the prism,
are said to be the most refrangible rays, and consequently are situated
in the most refrangible end or part of the spectrum, namely, that
farthest from the original direction of the incident white light. These
most refrangible rays are the violet, and we pass on to the least
refrangible end, the red, through bluish-violet, blue, bluish-green,
green, greenish-yellow, yellow, and orange. If you placed a prism say in
the red part of the spectrum, and caught some of those red rays and
allowed them to pass through your prism, and then either looked at the
emerging light or let it fall on a white surface, you would find only
red light would come through, only red rays. That light has been once
analysed, and it cannot be further broken up. There is great diversity
of shades, but only a limited number of primary impressions. Of these
primary impressions there are only four--red, yellow, green, and blue,
together with white and black. White is a collective effect, whilst
black is the antithesis of white and the very negation of colour. The
first four are called primary colours, for no human eye ever detected in
them two different colours, while all of the other colours contain two
or more primary colours. If we mix the following tints of the spectrum,
_i.e._ the following rays of coloured light, we shall produce white
light, red and greenish-yellow, orange and Prussian blue, yellow and
indigo blue, greenish-yellow and violet. All those pairs of colours that
unite to produce white are termed complementary colours. That is, one is
complementary to the other. Thus if in white light you suppress any one
coloured strip of rays, which, mingled uniformly with all the rest of
the spectral rays, produces the white light, then that light no longer
remains white, but is tinged with some particular tint. Whatever colour
is thus suppressed, a particular other tint then pervades the residual
light, and tinges it. That tint which thus makes its appearance is the
one which, with the colour that was suppressed, gave white light, and
the one is complementary to the other. Thus white can always be
compounded of two tints, and these two tints are complementary colours.
But it is important to remark here that I am now speaking of rays of
coloured light proceeding to and striking the eye; for a question like
this might be asked: "You say that blue and yellow are complementary
colours, and together they produce white, but if we mix a yellow and a
blue paint or dye we have as the result a green colour. How is this?"
The cases are entirely different, as I shall proceed to show. In
speaking of the first, the complementary colours, we speak of pure
spectral colours, coloured rays of light; in the latter, of pigment or
dye colours. As we shall see, in the first, we have an addition direct
of coloured lights producing white; in the latter, the green colour,
appearing as the result of the mixture of the blue and yellow pigments,
is obtained by the subtraction of colours; it is due to the absorption,
by the blue and yellow pigments, of all the spectrum, practically,
except the green portion. In the case of coloured objects, we are then
confronted with the fact that these objects appear coloured because of
an absorption by the colouring matter of every part of the rays of light
falling thereupon, except that of the colour of the object, which colour
is thrown off or reflected. This will appear clearer as we proceed. Now
let me point out a further fact and indicate another step which will
show you the value of such knowledge as this if properly applied. I said
that if we selected from the coloured light spectrum, separated from
white light by a prism, say, the orange portion, and boring a hole in
our screen, if we caught that orange light in another prism, it would
emerge as orange light, and suffer no further analysis. It cannot be
resolved into red and yellow, as some might have supposed, it is
monochromatic light, _i.e._ light purely of one colour. But when a
mixture of red and yellow light, which means, of course, a mixture of
rays of greater and less refrangibility respectively than our spectral
orange, the monochromatic orange--is allowed to strike the eye, then we
have again the impression of orange. How are we to distinguish a pure
and monochromatic orange colour from a colour produced by a mixture of
red and yellow? In short, how are we to distinguish whether colours are
homogeneous or mixed? The answer is, that this can only be done by the
prism, apart from chemical analysis or testing of the substances.

[Illustration: FIG. 16.]

The spectroscope is a convenient prism-arrangement, such that the
analytical effect produced by that prism is looked at through a
telescope, and the light that falls on the prism is carefully preserved
from other light by passing it along a tube after only admitting a small
quantity through a regulated slit.

Now all solid and liquid bodies when raised to a white heat give a
continuous spectrum, one like the prismatic band already described, and
one not interrupted by any dark lines or bands. The rays emitted from
the white-hot substance of the sun have to pass, before reaching our
earth, through the sun's atmosphere, and since the light emitted from
any incandescent body is absorbed on passing through the vapour of that
substance, and since the sun is surrounded by such an atmosphere of the
vapours of various metals and substances, hence we have, on examining
the sun's spectrum, instead of coloured bands or lines only, many dark
ones amongst them, which are called Fraunhofer's lines. Ordinary
incandescent vapours from highly heated substances give discontinuous
spectra, _i.e._ spectra in which the rays of coloured light are quite
limited, and they appear in the spectroscope only as lines of the
breadth of the slit. These are called line-spectra, and every chemical
element possesses in the incandescent gaseous state its own
characteristic lines of certain colour and certain refrangibility, by
means of which that element can be recognised. To observe this you place
a Bunsen burner opposite the slit of the spectroscope, and introduce
into its colourless flame on the end of a platinum wire a little of a
volatile salt of the metal or element to be examined. The flame of the
lamp itself is often coloured with a distinctiveness that is sufficient
for a judgment to be made with the aid of the naked eye alone, as to the
metal or element present. Thus soda and its salts give a yellow flame,
which is absolutely yellow or monochromatic, and if you look through
your prism or spectroscope at it, you do not see a coloured rainbow band
or spectrum, as with daylight or gaslight, but only one yellow double
line, just where the yellow would have been if the whole spectrum had
been represented. I think it is now plain that for the sake of
observations and exact discrimination, it is necessary to map out our
spectrum, and accordingly, in one of the tubes, the third, the
spectroscope is provided with a graduated scale, so adjusted that when
we look at the spectrum we also see the graduations of the scale, and so
our spectrum is mapped; the lines marked out and named with the large
and small letters of the alphabet, are certain of the prominent
Fraunhofer's lines (see A, B, C, a, d, etc., Fig. 16). We speak, for
example, of the soda yellow-line as coinciding with D of the spectrum.
These, then, are spectra produced by luminous bodies.

The colouring matters and dyes, their solutions, and the substances dyed
with them, are not, of course, luminous, but they do convert white light
which strikes upon or traverses them into coloured light, and that is
why they, in fact, appear either as coloured substances or solutions.
The explanation of the coloured appearance is that the coloured
substances or solutions have the power to absorb from the white light
that strikes or traverses them, all the rays of the spectrum but those
which are of the colour of the substance or solution in question, these
latter being thrown off or reflected, and so striking the eye of the
observer. Take a solution of Magenta, for example, and place a light
behind it. All the rays of that white light are absorbed except the red
ones, which pass through and are seen. Thus the liquid appears red. If a
dyed piece be taken, the light strikes it, and if a pure red, from that
light all the rays but red are absorbed, and so red light alone is
reflected from its surface. But this is not all with a dyed fabric, for
here the light is not simply reflected light; part of it has traversed
the upper layers of that coloured body, and is then reflected from the
interior, losing a portion of its coloured rays by absorption. This
reflected coloured light is always mixed with a certain amount of white
light reflected from the actual surface of the body before penetrating
its uppermost layer. Thus, if dyed fabrics are examined by the
spectroscope, the same appearances are generally observed as with the
solution of the corresponding colouring matters. An absorption spectrum
is in each case obtained, but the one from the solution is the purer,
for it does not contain the mixed white light reflected from the
surfaces of coloured objects. Let us now take an example. We will take a
cylinder glass full of picric acid in water, and of a yellow colour. Now
when I pass white light through that solution and examine the emerging
light, which looks, to my naked eye, yellow, I find by the spectroscope
that what has taken place is this: the blue part of the spectrum is
totally extinguished as far as G and 2/3 of F. That is all. Then why,
say you, does that liquid look yellow if all the rest of those rays pass
through and enter the eye, namely, the blue-green with a trifle of blue,
the green, yellow, orange, and red? The reason is this: we have already
seen that the colours complementary to, and so producing white light
with red, are green and greenish-blue or bluish-green. Hence these
cancel, so to say, and we only see yellow. We do not see a pure yellow,
then, in picric acid, but yellow with a considerable amount of white.
Here is a piece of scarlet paper. Why does it appear scarlet? Because
from the white light falling upon it, it practically absorbs all the
rays of the spectrum except the red and orange ones, and these it
reflects. If this be so, then, and we take our spectrum band of
perfectly pure colours and pass our strip of scarlet paper along that
variously coloured band of light, we shall be able to test the truth of
several statements I have made as to the nature of colour. I have said
colour is only an impression, and not a reality; and that it does not
exist apart from light. Now, I can show you more, namely, that the
colour of the so-called coloured object is entirely dependent on the
existence in the light of the special coloured rays which it radiates,
and that this scarlet paper depends on the red light of the spectrum for
the existence of its redness. On passing the piece of scarlet paper
along the coloured band of light, it appears red only when in the red
portion of the spectrum, whilst in the other portions, though it is
illumined, yet it has no colour, in fact it looks black. Hence what I
have said is true, and, moreover, that red paper looks red because, as
you see, it absorbs and extinguishes all the rays of the spectrum but
the red ones, and these it radiates. A bright green strip of paper
placed in the red has no colour, and looks black, but transferred to the
pure green portion it radiates that at once, does not absorb it as it
did the red, and so the green shines out finely. I have told you that
sodium salts give to a colourless flame a fine monochromatic or pure
yellow colour. Now, if this be so, and if all the light available in
this world were of such a character, then such a colour as blue would be
unknown. We will now ask ourselves another question, "We have a new blue
colouring matter, and we desire to know if we may expect it to be one of
the greatest possible brilliancy, what spectroscopic conditions ought it
to fulfil?" On examining a solution of it, or rather the light passing
through a solution of it, with the spectroscope, we ought to find that
all the rays of the spectrum lying between and nearly to H and b (Fig.
16), _i.e._ all the bluish-violet, blue, and blue-green rays pass
through it unchanged, unabsorbed, whilst all the rest should be
completely absorbed. In like manner a pure yellow colour would allow all
the rays lying between orange-red and greenish-yellow (Fig. 16) to pass
through unchanged, but would absorb all the other colours of the
spectrum.

Now we come to the, for you, most-important subject of mixtures of
colours and their effects. Let us take the popular case of blue and
yellow producing green. We have seen that the subjective effect of the
mixture of blue and yellow light on the eye is for the latter to lose
sense of colour, since colour disappears, and we get what we term white
light; in strict analogy to this the objective effect of a pure yellow
pigment and a blue is also to destroy colour, and so no colour comes
from the object to the eye; that object appears black. Now the pure blue
colouring matter would not yield a green with the pure yellow colouring
matter, for if you plot off the two absorption spectra as previously
described, on to the spectrum (Fig. 16), you will find that all the rays
would be absorbed by the mixture, and the result would be a black. But,
now, suppose a little less pure yellow were taken, one containing a
little greenish-yellow and a trifle of green, and also a little
orange-red on the other side to red, then whereas to the eye that yellow
might be as good as the first; now, when mixed with a blue, we get a
very respectable green. But, and this is very important, although of the
most brilliant dyes and colours there are probably no two of these that
would so unite to block out all the rays and produce black, yet this
result can easily and practically be arrived at by using three colouring
matters, which must be as different as possible from one another. Thus a
combination of a red, a yellow, and a blue colouring matter, when
concentrated enough, will not let any light pass through it, and can
thus be used for the production of blacks, and this property is made use
of in dyeing. And now we see why a little yellow dye is added to our
coal-tar black. A purplish shade would else be produced; the yellow used
is a colour complementary to that purple, and it absorbs just those blue
and purple rays of the spectrum necessary to illuminate by radiation
that purple, and _vice versâ_; both yellow and purple therefore
disappear. In like manner, had the black been of a greenish shade, I
should have added Croceine Orange, which on the fabric would absorb just
those green and bluish rays of light necessary to radiate from and
illumine that greenish part, and the greenish part would do the like by
the orange rays; the effects would be neutralised, and all would fall
together into black.

THE END.



INDEX


Acetone, 64

Acid, boric. _See_ Boric acid.
  "   carbolic. _See_ Phenol.
  "   colours, mordanting, 74
  "   hydrochloric. _See_ Hydrochloric acid.
  "   nitric. _See_ Nitric acid.
  "   sulphuric. _See_ Sulphuric acid.

Acids, distinguishing, from alkalis, 23, 49
  "    neutralisation of, 50
  "    properties of, 49
  "    specific gravities of, 49

Affinity, chemical, 71

Alizarin, 75, 76, 80, 83, 91, 99
  "       blue, 90
  "       paste, 91
  "       pure, 91
  "       purple, 77
  "       red, 77

Alkali, manufacture of, by ammonia-soda process, 55
  "     manufacture of, by electrolytic process, 56
  "     manufacture of, by Leblanc process, 53

Alkalis, distinguishing, from acids, 23, 49
  "      neutralisation of, 50
  "      properties of, 49
  "      specific gravities of, 49

Alum, cake, 73

Aluminium sulphate, 73

Ammonia, 23, 95

Ammonia-soda process, 55

Aniline, 91
  "      black, 81
  "      constitution of, 96
  "      preparation of, 96
  "      reaction of 97
  "      violet 77, 81

Animal fibres. _See_ Fibres.

Annatto, 83, 85, 87

Anthracene, 90

Archil. _See_ Orchil.

Aurin, 91, 98

Azo dyestuffs, 98


Barwood, 99

Basic colours or dyestuffs, mordanting, 76

Bast fibres. _See_ Fibres.

Bastose, 4

Bastose, distinction between, and cellulose, 4

Beaumé hydrometer degrees, 31

Benzene, 90, 96

Bixin, 88

Black-ash process, 54

Blue colour, absorption spectrum of pure, 114

Boilers, incrustations in, 42

Boiling-point, effect of pressure on, 32
  "           of water, effect of dissolved salts on, 36
  "           of water, effect of increase of pressure on, 35

Borax, 59
  "    tests of purity of, 59

Boric acid, 57

Boronitrocalcite, 59

Brasilin, 99

Brazil wood, 99


Camwood, 99

Carbolic acid. _See_ Phenol.

Carminic acid, 76

Carré ice-making machine, 32

Carrotting. _See_ Sécretage.

Carthamic acid, 87

Carthamin, 87

Cellulose, action of cupric-ammonium solutions on, 5
  "        composition of,   3
  "        distinction between, and bastose, 4
  "        properties of pure,   5

Cholesterol, 100

Chrome mordanting, 78

Chrome orange, 84
  "    yellow, 84

Chroming, over-, 78

Clark's soap test, 43

Coal-tar, 90
  "       yield of valuable products from, 90

Cochineal, 75, 76, 82, 83, 99

Coerulein, 90

Colour, absorption spectrum of pure blue, 114
  "     absorption spectrum of pure yellow, 114
  "     acids, 77
  "     bases, 77
  "     nature of, 107

Coloured substances, spectra of, 112

Colours, acid, mordanting of, 74
  "      basic, 75
  "      classification of, 79
  "      complementary, 109
  "      mixed, spectra of, 115
  "      pigment, 110
  "      primary, 110
  "      spectral, 110

Conditioning establishments, 21

Congo red, 71

Copper salts, dissolving, in iron pans, 39
  "           wet method of extracting, 38

Corrosion caused by fatty acids, 35

Cotton and woollen goods, separation of mixed, 5

Cotton fibre, action of basic zinc chloride on, 5
  "           composition of, 3
  "           dimensions of, 2
  "           stomata in cuticle of, 2
  "           structure of, 1

Cotton-silk fibre, 3
  "     "         composition of, 3

Crookes' heat-indicating paint, 107

Cudbear, 86

Cupric ammonium solution, action of, on cellulose, 5

Curcumin, 87


Dextrin, 4

Dyeing felt hats deep black, 106
  "     "        effect of stiffening and proofing process in, 65, 103
  "    of wool and felt with coal-tar colours, 105
  "    of wool and fur, 100
  "    power of coal-tar dyestuffs, 93
  "    with mixed coal-tar colours, 106

Dyestuffs, adjectiv, 83, 99
  "        azo, 98
  "        classification of, 79
  "        coal-tar,   90
  "          "       dyeing power of, 93
  "          "       yield of, 91
  "        mineral, 83
  "        monogenetic, 81
  "        pigment, 83
  "        polygenetic, 82
  "        substantive, 83
  "             "       artificial, 89
  "             "       natural, 85


Equivalence, law of, 49


Fats, decomposition of, by superheated steam, 35

Felt, dyeing, deep black, 106
    "   " with coal-tar colours, 105

Felting, dilute acid for promoting, 22
  "      effect of water in, 21
  "      fur, 15
  "      interlocking of scales in, 13
  "      preparation of fur for, 18
  "      unsuitability of dead wool for, 18

Fibre, cotton. _See_ Cotton.
  "    cotton-silk. _See_ Cotton-silk.
  "    flax. _See_ Flax.
  "    jute. _See_ Jute.
  "    silk. _See_ Silk.
  "    wool. _See_ Wool.

Fibres, action of acids on textile, 5
    "     "       alkaline solution of copper and glycerin on textile, 28
    "     "       alkalis on textile, 5
    "     "       caustic soda on textile , 28
    "     "       copper-oxide-ammonia on textile, 28
    "     "       nitric acid on textile, 28
    "     "       steam on textile, 5
    "     "       sulphuric acid on textile, 27

Fibres, animal, 6
  "     bast, 3
  "     vegetable, 1
  "       "        and animal, determining, in mixture, 27
  "       "        and animal, distinguishing, 4, 5
  "       "        and animal, distinguishing and separating, 24

Fibroïn, 7

Flax fibre, action of basic zinc chloride on, 5
  "         composition of, 3
  "         structure of, 2

Fraunhofer's lines, 111, 112

Fur, 8
  "  action of acids on, 23
  "    "    of alkalis on, 24
  "    "    on, in sécretage process, 17
  "  chrome mordanting of, 77
  "  composition of, 22
  "  felting, 15
  "  finish and strength of felted, effect of boiling water on, 22
  "  hygroscopicity of, 20
  "  preparation of, for felting, 18
  "  sécretage or carrotting of, 17
  "  stiffening and proofing of felted, 66
  "  sulphur in, reagents for detection of, 26

Fustic, 99


Gallein, 82, 83

Gallnuts, 99

Garancine, 99

Guy-Lussac tower, 52

Glover tower, 52

Glucose, 4

Greening of black hats, 65


Hæmatein, 76, 78 83, 99

Hair, 8
  "  cells from, 11
  "  distinction between, and wool, 12, 14
  "  dyeing, 26
  "  growth of, 8
  "  scales from, 11
  "   "     of, action of reagents on, 12
  "  scaly structure of, 11
  "  structure of, 8, 9
  "  sulphur in, reagents for detection of, 26

Hargreaves & Robinson's process, 53

Hats dyed logwood black, deterioration of, 104
  "  greening of black, 65
  "  stiffening and proofing of, 63, 64
  "  stiffening and proofing of, by Cheetham's process, 66
  "  stiffening and proofing of, by Continental process, 66
  "  stiffening and proofing process, effect of, in dyeing, 65, 103

Heat, latent, 32, 33
  "     " of steam, 34
  "     " of water, 34

Heddebault's process of separating mixed cotton and woollen goods, 5

Hydrochloric acid, manufacture of, by Hargreaves & Robinson's process, 53
   "          "    manufacture of, by salt-cake process, 53


Ice, heat of liquefaction of, 34

Ice-making machine, Carré, 32

Indican, 85

Indicators, 50, 70

Indigo, 85
  "     artificial, 86
  "     blue, 85
  "     recovery of, from indigo-dyed woollen goods, 24
  "     vat, 86
  "     white, 85

Insoluble compounds, precipitation of, from solutions, 38

Iron liquor. _See_ Mordant, iron.


Jute fibre, 3
  "  composition of, 4


Lac, button, 63
  "  dye, 62, 99
  "  seed, 62
  "  stick, 62
  _See also_ Shellac.

Lakes, colour, 75

Latent heat. _See_ Heat.

Leblanc process, 53

Light, analysis of white, 107
  " composition of white, 107
  " homogeneous or monochromatic, 108, 110
  " rays, refraction of, 108

Linen fibre. _See_ Flax.

Litmus, 70, 86

Logwood, 75, 76, 78, 83, 99

Logwood black, 78, 81, 104
  "       "   deterioration of hats dyed with, 104


Madder, 80, 83, 99

Magenta, 76, 80, 83, 91, 97

Marsh gas, 95

Mercuric nitrate, use of, for the sécretage of fur, 17

Merino wool, 15

Methane. _See_ Marsh gas.

Methyl alcohol. _See_ Wood spirit.
  "    green, 97
  "     violet, 97

Mirbane, essence of, 96

Molisch's test, 4

Mordant, alumina, 64, 75
  "      antimony, 76
  "      iron, 64, 76
  "      tannin, 76
  "      tin, 76

Mordanting acid (phenolic) colours, 74
  "        basic colours, 76
  "        chrome, 77
  "        woollen fabrics, 75

Mordants, 69
  "       fatty acid, 77


Naphthalene, 90, 98

Naphthol yellow, 91

Naphthols, 91, 98

Naphthylamine, 91

Nitric acid, 95
  " manufacture of, 52

Nitrobenzene, 96

Nitroprusside of soda, 26

Oils, decomposition of, by superheated steam, 35

Orcèin, 86

Orchil, 85, 86

Orcin, 86

Orellin, 88

Over-chroming, _See_ Chroming.


Paint, Crookes' heat-indicating, 107

Persian berries, 75, 99

Phenol, 90
   "   constitution of, 98

Phenolic colours. _See_ Acid colours.

Phenolphthalein, 70

Picric acid, 81, 91
  "         absorption spectrum of, 113
  "         constitution of, 98

Plumbate of soda, 26

Potassium, decomposition of water by, 25, 30

Proofing mixture, 63
   "     process, 64
   "        "     Cheetham's, 66
   "        "     Continental, 66
   "        "     effect of, in dyeing, 65, 103

Purpurin, 99


Quercitron, 99


Red liquor. See Mordant, alumina.

Refraction of light rays, 108


Safflower, 85, 87

Salt-cake process, 53

Salts, 49
  "   acid, 70, 71
  "   basic, 71
  "   neutral or normal, 71
  "  stable, 72
  "  unstable, 72

Santalin, 99

Santalwood, 99

Sealing-wax, coloured, 103

Sécretage of fur, 17
    "    process, injury to fur in, 17

Sericin, 7

Shellac, 62
   "   colouring of, 103
   "   rosin in, detection of, 63
   "   solvents for, 63
  _See also_ Lac.

Silk fibre, action of acids on, 7
 "     "      "    of alkaline solution of, copper and glycerin on, 7
 "     "      "    of alkalis on, 7
 "     "      "    of basic zinc chloride on, 7
 "     "  bleaching of, 7
 "     "  composition of, 7
 "     "  structure of, 6
 "     "  ungumming of, 7
 "   glue, 7
 "   gum, 7

Soap, 60
  "   alkali in, detection of, 61
  "   oleic acid, 101
  "   palm oil, 101
  "   water in, determination of, 60

Soda. _See_ Alkali.

Solution, 36
    "    precipitation of insoluble compounds from, 38

Specific gravity, 30

Spectra of coloured substances 112

Spectroscope, 111

Spectrum, 108
  "       absorption, 113
  "       continuous, 111
  "       discontinuous or line, 111

Spirits of salt. _See_ Hydrochloric acid.

Starch, 4

Steam, 31
  "    latent heat of, 34

Stiffening mixture, 63
  "        process, 64
  "          "      Cheetham's, 66
  "          "      Continental, 66
  "          "      effect of, in dyeing 65, 103

Suint. _See_ Wool grease.

Sulphur in wool, fur, and hair, reagents for detection of, 26

Sulphuric acid, manufacture of, 50
  "         "       "       by contact process, 52
  "         "       "       by lead chamber process, 51

Sumach, 99


Tannins, 99

Tincal, 59

Tiza, 59

Toluene, 90

Toluidine, 91

Turmeric, 80, 83, 85, 87

Twaddell hydrometer degrees, 31


Ultramarine blue, 81

Ultramarine green, 81
  "         rose-coloured, 81


Valency, 71

Vegetable fibres. _See_ Fibres.

Veneering process, 66

Vermilline scarlet, 91

Vitriol. _See_ Sulphuric acid.


Water, 29
  "    boiling of 31
  "    boiling-point of, effect of dissolved salts on 36
  "    boiling-point of, effect of increase of pressure on, 35
  "    chlorides in, detection of, 47
  "    composition of, 29
  "    contamination of, by factories, 45
  "    copper in, detection of, 46
  "    decomposition of, by potassium, 25, 30
  "    filtration of, 47
  "    hard, 41, 42
  "      "   Clark's soap test for, 43
  "      "   softening of, 41
  "      "   waste of soap by, 43
  "    hardness, temporary and permanent, of, 42
  "    impurities in, 42
  "      "        effect of, in dyeing, 42
  "      "        ferruginous, 44
  "    iron in, detection of, 46
  "    latent heat of, 34
  "    lead in, detection of, 47
  "    lime in, detection of, 46
  "    magnesium in, detection of, 46
  "    purification of, 45
  "    purity of, tests for, 46
  "    soft, 40
  "    effect of carbonic acid in hardening, 40
  "    sulphates in, detection of, 24

Wood acid, 64
  "  destructive distillation of, 64
  "  spirit, 64

Wool, chrome mordanting of, 77
  "   dead: why it will not felt, 18
  "   dyeing, with coal-tar colours, 105
  "   felted, effect of boiling water on finish and strength of, 22
  "   felted, effect of stiffening process on finish of, 66, 103
  "   felting of, interlocking of scales in, 13
  "   fibre, 8
  "     "   action of acids on, 23
  "     "     "    of alkalis on, 24
  "     "   composition of, 22
  "     "   curly structure of, 15
  "     "   distinction between, and hair, 12, 14
  "     "   growth of, 8
  "     "   hygroscopicity of, 20
  "     "   structure of, from diseased sheep, 19
  "     "   sulphur in, reagents for detection of, 26
  "   grease, 100
  "   kempy, 19
  "   merino, 15
  "   mordanting, 75
  "   scouring, 101
  "   stripping of, 23

Woollen goods, indigo-dyed, recovery of indigo from, 24
  "       "    mixed cotton and, separation of, 5


Xylenes, 90


Yellow colour, absorption spectrum of pure, 114

Yolk. _See_ Wool grease.



Abridged Catalogue

OF

_Special Technical Books_.


INDEX TO SUBJECTS.

PAGE

Agricultural Chemistry,             9
Air, Industrial Use of,            10
Alum and its Sulphates,             8
Ammonia,                            8
Aniline Colours,                    3
Animal Fats,                        6
Anti-corrosive Paints,              4
Architecture, Terms in,            22
Architectural Pottery,             12
Artificial Perfumes,                7

Balsams,                            9
Bleaching,                         17
Bleaching Agents,                  17
Bone Products,                      8
Bookbinding,                       23
Brick-making,                  11, 12
Burnishing Brass,                  20


Carpet Yarn Printing,              16
Casein,                             4
Celluloid,                         23
Cement,                            22
Ceramic Books,                     11
Charcoal,                           8
Chemical Essays,                    8
Chemical Works,                     8
Chemistry of Pottery,              12
Clay Analysis,                     12
Coal dust Firing,                  19
Colour Matching,                   16
Colliery Recovery Work,            18
Colour-mixing for Dyers,           16
Colour Theory,                     16
Combing Machines,                  18
Compounding Oils,                   6
Condensing Apparatus,              19
Cosmetics,                          7
Cotton Dyeing,                     17
Cotton Spinning,               17, 18
Cotton Waste,                      18

Damask Weaving,                    15
Dampness in Buildings,             22
Decorators' Books,                  4
Decorative Textiles,               15
Dental Metallurgy,                 19
Drugs,                             22
Drying Oils,                        5
Drying with Air,                   10
Dyeing Marble,                     23
Dyeing Woollen Fabrics,            17
Dyers' Materials,                  16
Dye-stuffs,                        17

Edible Fats and Oils,               7
Electric Wiring,               20, 21
Electricity in Collieries,         19
Emery,                             24
Enamelling Metal,              13, 21
Enamels,                           13
Engineering Handbooks,             20
Engraving,                         23
Essential Oils,                     7
Evaporating Apparatus,              9
External Plumbing,                 20

Fats,                               6
Faults in Woollen Goods,           15
Flax Spinning,                     18
Food and Drugs,                    22
Fruit Preserving,                  22

Gas Firing,                        19
Glass-making Recipes,              13
Glass Painting,                    13
Glue-making and Testing,            8
Greases,                            6
Gutta Percha,                      11

Hat Manufacturing,                 15
Hemp Spinning,                     18
History of Staffs Potteries        12
Hops,                              21
Hot-water Supply,                  21

India-rubber,                      11
Industrial Alcohol,                 9
Inks,                      3, 4, 5, 9
Iron-corrosion,                     4
Iron, Science of,                  19

Japanning,                         21
Jute Spinning,                     18

Lace-Making,                       15
Lacquering,                        20
Lake Pigments,                      3
Lead and its Compound,             10
Leather-working Mater'ls,       6, 11
Libraries,                         24
Linoleum,                           5
Lithography,                       23
Lubricants,                         6

Manures,                         8, 9
Meat Preserving,                   22
Mineral Pigments,                   3
Mineral Waxes,                      6
Mine Ventilation,                  18
Mine Haulage,                      18
Mining, Electricity,               19

Needlework,                        15

Oil and Colour Recipes,             3
Oil Boiling,                        5
Oil Merchants' Manual,              6
Oils,                               6
Ozone, Industrial Use of,          10

Paint Manufacture,                  3
Paint Materials,                    3
Paint-material Testing,             4
Paint Mixing,                       3
Paper-Mill Chemistry,              13
Paper-pulp Dyeing,                 13
Petroleum,                          6
Pigments, Chemistry of,             3
Plumbers' Work,                    20
Pottery Clays,                     12
Pottery Decorating,                11
Pottery Manufacture,               11
Pottery Marks,                     12
Power-loom Weaving,                14
Preserved Foods,                   22
Printers' Ready Reckoner           23
Printing Inks,                3, 4, 5

Recipes,                            3
Resins,                             9
Ring Spinning Frame,               18
Risks of Occupations,              10
Riveting China, etc.,              12

Sanitary Plumbing,                 20
Scheele's Essays,                   8
Sealing Waxes,                      9
Shale Tar Distillation,             8
Shoe Polishes,                      6
Silk Dyeing,                       17
Silk Throwing,                     17
Smoke Prevention,                  19
Soaps,                              7
Spinning,                  15, 17, 18
Spirit Varnishes,                   5
Staining Marble, and Bone,         23
Steam Drying,                      10
Steel Hardening,                   19
Sugar Refining,                    23
Sweetmeats,                        22

Technical Schools, List,           24
Terra-cotta,                       11
Testing Paint Materials,            4
Testing Yarns,                     15
Textile Fabrics,               14, 15
Textile Fibres,                    14
Textile Materials,                 14
Timber,                            21

Varnishes,                          5
Vegetable Fats,                     7
Vegetable Preserving,              22

Warp Sizing,                       16
Waste Utilisation,                  9
Water, Industrial Use,             10
Water-proofing Fabrics,            16
Waxes, 6
Weaving Calculations,              15
White Lead and Zinc,                5
Wood Distillation,                 21
Wood Extracts,                     21
Wood Waste Utilisation,            22
Wood-Dyeing,                       23
Wool-Dyeing,                       17
Woollen Goods,             15, 16, 17
Writing Inks,                       9

X-Ray Work,                        11

Yarn Sizing,                       16
Yarn Testing,                      15

Zinc White Paints,                  5


PUBLISHED BY
SCOTT, GREENWOOD & SON
8 BROADWAY, LUDGATE, LONDON, E.C.



FULL PARTICULARS OF CONTENTS

Of the Books mentioned in this ABRIDGED CATALOGUE will be found in the
following Catalogues of

CURRENT TECHNICAL BOOKS.


LIST I.

Artists' Colours--Bone Products--Butter and Margarine
Manufacture--Casein--Cements--Chemical Works (Designing and
Erection)--Chemistry (Agricultural, Industrial, Practical and
Theoretical)--Colour Mixing--Colour Manufacture--Compounding
Oils--Decorating--Driers--Drying Oils--Drysaltery--Emery--Essential
Oils--Fats (Animal, Vegetable, Edible)--Gelatines--Glues--Greases--
Gums--Inks--Lead--Leather--Lubricants--Oils--Oil Crushing--Paints--Paint
Manufacturing--Paint Material Testing--Perfumes--Petroleum--Pharmacy--
Recipes (Paint, Oil and Colour)--Resins--Sealing Waxes--Shoe
Polishes--Soap Manufacture--Solvents--Spirit Varnishes--Varnishes--White
Lead--Workshop Wrinkles.


LIST II.

Bleaching--Bookbinding--Carpet Yarn Printing--Colour (Matching, Mixing,
Theory)--Cotton Combing Machines--Dyeing (Cotton, Woollen and Silk
Goods)--Dyers' Materials--Dye-stuffs--Engraving--Flax, Hemp and Jute
Spinning and Twisting--Gutta-Percha--Hat
Manufacturing--India-rubber--Inks--Lace-making--Lithography--Needlework--Paper
Making--Paper-Mill Chemist--Paper-pulp Dyeing--Point Lace--Power-loom
Weaving--Printing Inks--Silk Throwing--Smoke
Prevention--Soaps--Spinning--Textile (Spinning, Designing, Dyeing,
Weaving, Finishing)--Textile Materials--Textile Fabrics--Textile
Fibres--Textile Oils--Textile Soaps--Timber--Water (Industrial
Uses)--Water-proofing--Weaving--Writing Inks--Yarns (Testing, Sizing).


LIST III.

Architectural Terms--Brassware (Bronzing, Burnishing, Dipping,
Lacquering)--Brickmaking--Building--Cement Work--Ceramic
Industries--China--Coal-dust Firing--Colliery
Books--Concrete--Condensing Apparatus--Dental
Metallurgy--Drainage--Drugs--Dyeing--Earthenware--Electrical
Books--Enamelling--Enamels--Engineering Handbooks--Evaporating
Apparatus--Flint Glass-making--Foods--Food Preserving--Fruit
Preserving--Gas Engines--Gas Firing--Gearing--Glassware (Painting,
Riveting)--Hops--Iron (Construction, Science)--Japanning--Lead--Meat
Preserving--Mines (Haulage, Electrical Equipment, Ventilation, Recovery
Work from)--Plants (Diseases, Fungicides, Insecticides)--Plumbing
Books--Pottery (Architectural, Clays, Decorating, Manufacture, Marks
on)--Reinforced Concrete--Riveting (China, Earthenware,
Glassware)--Steam Turbines--Sanitary Engineering--Steel (Hardening,
Tempering)--Sugar--Sweetmeats--Toothed Gearing--Vegetable
Preserving--Wood Dyeing--X-Ray Work.

COPIES OF ANY OF THESE LISTS WILL BE SENT POST FREE ON APPLICATION.


(Paints, Colours, Pigments and Printing Inks.)

THE CHEMISTRY OF PIGMENTS. By ERNEST J. PARRY, B.Sc. (Lond.),
F.I.C., F.C.S., and J.H. COSTE, F.I.C., F.C.S. Demy 8vo. Five
Illustrations. 285 pp. Price 10s. 6d. net. (Post free, 10s. 10d. home;
11s. 3d. abroad.)

THE MANUFACTURE OF PAINT. A Practical Handbook for Paint
Manufacturers, Merchants and Painters. By J. CRUICKSHANK SMITH,
B.Sc. Demy 8vo. 200 pp. Sixty Illustrations and One Large Diagram. Price
7s. 6d. net. (Post free, 7s. 10d. home; 8s. abroad.)

DICTIONARY OF CHEMICALS AND RAW PRODUCTS USED IN THE MANUFACTURE OF
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HURST, F.C.S. Demy 8vo. 380 pp. Price 7s. 6d. net. (Post free, 8s.
home; 8s. 6d. abroad.)

THE MANUFACTURE OF LAKE PIGMENTS FROM ARTIFICIAL COLOURS. By
FRANCIS H. JENNISON, F.I.C., F.C.S. Sixteen Coloured Plates,
showing Specimens of Eighty-nine Colours, specially prepared from the
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THE MANUFACTURE OF MINERAL AND LAKE PIGMENTS. Containing Directions
for the Manufacture of all Artificial, Artists and Painters' Colours,
Enamel, Soot and Metallic Pigments. A text-book for Manufacturers,
Merchants, Artists and Painters, By Dr. JOSEF BERSCH.
Translated by A.C. WRIGHT, M.A. (Oxon.), B.Sc. (Lond.).
Forty-three Illustrations. 476 pp. Demy 8vo. Price 12s. 6d. net. (Post
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RECIPES FOR THE COLOUR, PAINT, VARNISH, OIL, SOAP AND DRYSALTERY
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Revised Edition. Demy 8vo. Price 10s. 6d. net. (Post free, 11s. home;
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OIL COLOURS AND PRINTERS' INKS. By LOUIS EDGAR ANDÉS.
Translated from the German. 215 pp. Crown 8vo. 56 Illustrations. Price
5s. net. (Post free, 5s. 4d. home; 5s. 6d. abroad.)

MODERN PRINTING INKS. A Practical Handbook for Printing Ink
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THREE HUNDRED SHADES AND HOW TO MIX THEM. For Architects, Painters and
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each Plate containing specimens of three artistic shades. These shades
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HOUSE DECORATING AND PAINTING. By W. NORMAN BROWN.
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A HISTORY OF DECORATIVE ART. By W. NORMAN BROWN. Thirty-nine
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and abroad.)

WORKSHOP WRINKLES. for Decorators, Painters, Paperhangers, and Others.
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net. (Post free, 2s. 9d. home; 2s. 10d. abroad.)

CASEIN. By ROBERT SCHERER. Translated from the German by
CHAS. SALTER. Demy 8vo. Illustrated. Second Revised English
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SIMPLE METHODS FOR TESTING PAINTERS' MATERIALS. By A.C.
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net. (Post free, 5s. 3d. home; 5s. 6d. abroad.)

IRON-CORROSION, ANTI-FOULING AND ANTI-CORROSIVE PAINTS. Translated
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275 pp. Demy 8vo. Price 10s. 6d. net. (Post free, 10s. 10d. home; 11s.
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THE TESTING AND VALUATION OF RAW MATERIALS USED IN PAINT AND COLOUR
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of Colour Works. 88 pp. Crown 8vo. Price 5s. net. (Post free, 5s. 3d.
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_For contents of these books, see List I._

THE MANUFACTURE AND COMPARATIVE MERITS OF WHITE LEAD AND ZINC WHITE
PAINTS. By G. PETIT, Civil Engineer, etc. Translated from the
French. Crown 8vo. 100 pp. Price 4s. net. (Post free, 4s. 3d. home; 4s.
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STUDENTS' HANDBOOK OF PAINTS, COLOURS, OILS AND VARNISHES. By JOHN
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(Post free, 2s. 9d. home and abroad.)


(Varnishes and Drying Oils.)

THE MANUFACTURE OF VARNISHES AND KINDRED INDUSTRIES. By J. GEDDES
MCINTOSH. Second, greatly enlarged, English Edition, in three
Volumes, based on and including the work of Ach. Livache.

VOLUME I.--OIL CRUSHING, REFINING AND BOILING, THE MANUFACTURE
OF LINOLEUM, PRINTING AND LITHOGRAPHIC INKS, AND INDIA-RUBBER
SUBSTITUTES. Demy 8vo. 150 pp. 29 Illustrations. Price 7s. 6d. net.
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VOLUME II.--VARNISH MATERIALS AND OIL-VARNISH MAKING. Demy
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VOLUME III.--SPIRIT VARNISHES AND SPIRIT VARNISH MATERIALS.
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home; 13s. 6d. abroad.)

DRYING OILS, BOILED OIL AND SOLID AND LIQUID DRIERS. By L.E.
ANDÉS. Expressly Written for this Series of Special Technical
Books, and the Publishers hold the Copyright for English and Foreign
Editions. Forty-two Illustrations. 342 pp. Demy 8vo. Price 12s. 6d. net.
(Post free, 13s. home; 13s. 3d. abroad.)

(_Analysis of Resins, see page 9._)


(Oils, Fats, Waxes, Greases, Petroleum.)

LUBRICATING OILS, PATS AND GREASES: Their Origin, Preparation,
Properties, Uses and Analyses. A Handbook for Oil Manufacturers,
Refiners and Merchants, and the Oil and Fat Industry in General. By
GEORGE H. HURST, F.C.S. Third Revised and Enlarged Edition.
Seventy-four Illustrations. 384 pp. Demy 8vo. Price 10s. 6d. net. (Post
free, 11s. home; 11s. 3d. abroad.)

TECHNOLOGY OF PETROLEUM: Oil Fields of the World--Their History,
Geography and Geology--Annual Production and Development--Oil-well
Drilling--Transport. By HENRY NEUBERGER and HENRY
NOALHAT. Translated from the French by J.G. MCINTOSH. 550
pp. 153 Illustrations. 26 Plates. Super Royal 8vo. Price 21s. net. (Post
free, 21s, 9d. home; 23s. 6d. abroad.)

MINERAL WAXES: Their Preparation and Uses. By RUDOLF
GREGORIUS. Translated from the German. Crown 8vo. 250 pp. 32
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THE PRACTICAL COMPOUNDING OF OILS, TALLOW AND GREASE FOR LUBRICATION,
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THE MANUFACTURE OF LUBRICANTS, SHOE POLISHES AND LEATHER DRESSINGS. By
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CHAS. SALTER. 10 Illustrations. Crown 8vo. 170 pp. Price 7s.
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THE OIL MERCHANTS' MANUAL AND OIL TRADE READY RECKONER. Compiled by
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7s. 10d. home; 8s. 3d. abroad.)

ANIMAL FATS AND OILS: Their Practical Production, Purification and
Uses for a great Variety of Purposes. Their Properties, Falsification
and Examination. Translated from the German of LOUIS EDGAR
ANDÉS. Sixty-two Illustrations. 240 pp. Second Edition, Revised and
Enlarged. Demy 8vo., Price 10s. 6d. net. (Post free, 10s. 10d. home;
11s. 3d. abroad.)

_For contents of these books, see List I._

VEGETABLE FATS AND OILS: Their Practical Preparation, Purification and
Employment for Various Purposes, their Properties, Adulteration and
Examination. Translated from the German of Louis EDGAR ANDÉS.
Ninety-four Illustrations. 340 pp. Second Edition. Demy 8vo. Price 10s.
6d. net. (Post free, 11s. home; 11s. 6d. abroad.)

EDIBLE FATS AND OILS: Their Composition, Manufacture and Analysis. By
W.H. SIMMONS, B.Sc. (Lond.), and C.A. MITCHELL, B.A.
(Oxon.). Demy 8vo. 150 pp. Price 7s. 6d. net. (Post free, 7s. 9d. home;
8s. abroad.)


(Essential Oils and Perfumes.)

THE CHEMISTRY OF ESSENTIAL OILS AND ARTIFICIAL PERFUMES. By ERNEST
J. PARRY, B.Sc. (Lond.), F.I.C., F.C.S. Second Edition, Revised and
Enlarged. 552 pp. 20 Illustrations. Demy 8vo. Price 12s. 6d. net. (Post
free, 13s. home; 13s. 6d. abroad.)


(Soap Manufacture.)

SOAPS. A Practical Manual of the Manufacture of Domestic, Toilet and
other Soaps. By GEORGE H. HURST, F.C.S. 2nd edition. 390 pp. 66
Illustrations. Demy 8vo. Price 12s. 6d. net. (Post free, 13s. home; 13s.
6d. abroad.)

TEXTILE SOAPS AND OILS. Handbook on the Preparation, Properties and
Analysis of the Soaps and Oils used in Textile Manufacturing, Dyeing and
Printing. By GEORGE H. HURST, F.C.S. Crown 8vo. 195 pp. 1904.
Price 5s. net. (Post free, 5s. 4d. home; 5s. 6d. abroad.)

THE HANDBOOK OF SOAP MANUFACTURE. By WM. H. SIMMONS, B.Sc.
(Lond.), F.C.S. and H.A. APPLETON. Demy 8vo. 160 pp. 27
Illustrations. Price 8s. 6d. net. (Post free, 8s. 10d. home; 9s.
abroad.)


(Cosmetical Preparations.)

COSMETICS: MANUFACTURE, EMPLOYMENT AND TESTING OF ALL COSMETIC
MATERIALS AND COSMETIC SPECIALITIES. Translated from the German of Dr.
THEODOR KOLLER. Crown 8vo. 262 pp. Price 5s. net. (Post free,
5s. 4d. home; 5s. 6d. abroad.)


(Glue, Bone Products and Manures.)

GLUE AND GLUE TESTING. By SAMUEL RIDEAL, D.Sc. (Lond.),
F.I.C. Fourteen Engravings. 144 pp. Demy 8vo. Price 10s. 6d. net. (Post
free, 10s. 10d. home; 11s. abroad)

BONE PRODUCTS AND MANURES: An Account of the most recent Improvements
in the Manufacture of Fat, Glue, Animal Charcoal, Size, Gelatine and
Manures. By THOMAS LAMBERT, Technical and Consulting Chemist.
Illustrated by Twenty-one Plans and Diagrams. 162 pp. Demy 8vo. Price
7s. 6d. net. (Post free, 7s. 10d. home; 8s. abroad.)

(_See also Chemical Manures, p. 9._)


(Chemicals, Waste Products, etc.)

REISSUE OF CHEMICAL ESSAYS OF C.W. SCHEELE. First Published in English
in 1786. Translated from the Academy of Sciences at Stockholm, with
Additions. 300 pp. Demy 8vo. Price 5s. net. (Post free, 5s. 6d. home;
5s. 9d. abroad.)

THE MANUFACTURE OF ALUM AND THE SULPHATES AND OTHER SALTS OF ALUMINA
AND IRON. Their Uses and Applications as Mordants in Dyeing and Calico
Printing, and their other Applications in the Arts Manufactures,
Sanitary Engineering, Agriculture and Horticulture. Translated from the
French of LUCIEN GESCHWIND. 195 Illustrations. 400 pp. Royal
8vo. Price 12s. 6d. net. (Post free, 13s. home; 13s. 6d. abroad.)

AMMONIA AND ITS COMPOUNDS: Their Manufacture and Uses. By CAMILLE
VINCENT, Professor at the Central School of Arts and Manufactures,
Paris. Translated from the French by M.J. SALTER. Royal 8vo.
114 pp. Thirty-two Illustrations. Price 5s. net. (Post free, 5s. 4d.
home; 5s. 6d. abroad.)

CHEMICAL WORKS: Their Design, Erection, and Equipment. By S.S.
DYSON and S.S. CLARKSON. Royal 8vo. 220 pp. With Plates
and Illustrations. Price 21s. net. (Post free, 21s. 6d. home; 22s.
abroad.)

SHALE TAR DISTILLATION: The Treatment of Shale and Lignite Products.
Translated from the German of W. SCHEITHAUER. [_In the Press_.

_For contents of these books, see List I._

INDUSTRIAL ALCOHOL. A Practical Manual on the Production and Use of
Alcohol for Industrial Purposes and for Use as a Heating Agent, as an
Illuminant and as a Source of Motive Power. By J.G. MCINTOSH,
Lecturer on Manufacture and Applications of Industrial Alcohol at The
Polytechnic, Regent Street, London. Demy 8vo. 1907. 250 pp. With 75
Illustrations and 25 Tables. Price 7s. 6d. net. (Post free, 7s. 9d.
home; 8s. abroad.)

THE UTILISATION OF WASTE PRODUCTS. A Treatise on the Rational
Utilisation, Recovery and Treatment of Waste Products of all kinds. By
Dr. THEODOR KOLLER. Translated from the Second Revised German
Edition. Twenty-two Illustrations. Demy 8vo. 280 pp. Price 7s. 6d. net.
(Post free, 7s. 10d. home; 8s. 3d. abroad.)

ANALYSIS OF RESINS AND BALSAMS. Translated from the German of Dr.
KARL DIETERICH. Demy 8vo. 340 pp. Price 7s. 6d. net. (Post
free, 7s. 10d. home; 8s. 3d. abroad.)


(Agricultural Chemistry and Manures.)

MANUAL OF AGRICULTURAL CHEMISTRY. By HERBERT INGLE, F.I.C.,
Late Lecturer on Agricultural Chemistry, the Leeds University; Lecturer
in the Victoria University. Second Edition, with additional matter
relating to Tropical Agriculture, etc. 438 pp. 11 Illustrations. Demy
8vo. Price 7s. 6d. net. (Post free, 8s. home; 8s. 6d. abroad.)

CHEMICAL MANURES. Translated from the French of J. FRITSCH.
Demy 8vo. Illustrated. 340 pp. Price 10s. 6d. net. (Post free, 11s.
home; 11s. 6d. abroad.)

(_See also Bone Products and Manures, p. 8._)


(Writing Inks and Sealing Waxes.)

INK MANUFACTURE: Including Writing, Copying, Lithographic, Marking,
Stamping, and Laundry Inks. By SIGMUND LEHNER. Three
Illustrations. Crown 8vo. 162 pp. Translated from the German of the
Fifth Edition. Price 5s. net. (Post free, 5s. 3d. home; 5s. 6d. abroad.)

SEALING-WAXES, WAFERS AND OTHER ADHESIVES FOR THE HOUSEHOLD, OFFICE,
WORKSHOP AND FACTORY. By H.C. STANDAGE, Crown 8vo. 96 pp.
Price 5s. net. (Post free, 5s. 3d. home; 5s. 4d. abroad.)


(Lead Ores and Lead Compounds.)

LEAD AND ITS COMPOUNDS. By THOS. LAMBERT, Technical and
Consulting Chemist. Demy 8vo. 226 pp. Forty Illustrations. Price 7s. 6d.
net. (Post free, 7s. 10d. home; 8s. 3d. abroad.)

NOTES ON LEAD ORES: Their Distribution and Properties. By JAS.
FAIRIE, F.G.S. Crown 8vo. 64 pages. Price 1s. net. (Post free, 1s.
3d. home; 1s. 4d. abroad.)

(_White Lead and Zinc White Paints, see p. 5._.)


(Industrial Hygiene.)

THE RISKS AND DANGERS TO HEALTH OF VARIOUS OCCUPATIONS AND THEIR
PREVENTION. By LEONARD A. PARRY, M.D., B.Sc. (Lond.). 196 pp.
Demy 8vo. Price 7s. 6d. net. (Post free, 7s. 10d. home; 8s. abroad.)


(Industrial Uses of Air, Steam and Water.)

DRYING BY MEANS OF AIR AND STEAM. Explanations, Formulæ, and Tables
for Use in Practice. Translated from the German of E.
HAUSBRAND. Two folding Diagrams and Thirteen Tables. Crown 8vo. 72
pp. Price 5s. net. (Post free, 5s. 3d. home; 5s. 6d. abroad.)

(_See also "Evaporating, Condensing and Cooling Apparatus," p. 19._)

PURE AIR, OZONE, AND WATER. A Practical Treatise of their Utilisation
and Value in Oil, Grease, Soap, Paint, Glue and other Industries. By
W.B. COWELL. Twelve Illustrations. Crown 8vo. 85 pp. Price 5s.
net. (Post free, 5s. 3d. home; 5s. 6d. abroad.)

THE INDUSTRIAL USES OF WATER.
COMPOSITION--EFFECTS--TROUBLES--REMEDIES--RESIDUARY
WATERS--PURIFICATION--ANALYSIS. By H. DE LA COUX. Royal 8vo.
Translated from the French and Revised by ARTHUR MORRIS. 364
pp. 135 Illustrations. Price 10s. 6d. net. (Post free, 11s. home; 11s.
6d. abroad.)

(_See Books on Smoke Prevention, Engineering and Metallurgy, p. 19,
etc._)

_For contents of these books, see List III._


(X Rays.)

PRACTICAL X RAY WORK. By FRANK T. ADDYMAN, B.Sc. (Lond.),
F.I.C., Member of the Roentgen Society of London; Radiographer to St.
George's Hospital; Demonstrator of Physics and Chemistry, and Teacher of
Radiography in St. George's Hospital Medical School. Demy 8vo. Twelve
Plates from Photographs of X Ray Work. Fifty-two Illustrations. 200 pp.
Price 10s. 6d. net. (Post free, 10s. 10d. home; 11s. 3d. abroad.)


(India-Rubber and Gutta Percha.)

INDIA-RUBBER AND GUTTA PERCHA. Second English Edition, Revised and
Enlarged. Based on the French work of T. SEELIGMANN, G.
LAMY TORRILHON and H. FALCONNET by JOHN GEDDES
MCINTOSH. Royal 8vo. 100 Illustrations. 400 pages. Price 12s. 6d.
net. (Post free, 13s. home; 13s. 6d. abroad.)


(Leather Trades.)

THE LEATHER WORKER'S MANUAL. Being a Compendium of Practical Recipes
and Working Formulæ for Curriers, Bootmakers, Leather Dressers, Blacking
Manufacturers, Saddlers, Fancy Leather Workers. By H.C.
STANDAGE. Demy 8vo. 165 pp. Price 7s. 6d. net. (Post free, 7s. 10d.
home; 8s. abroad.)

(_See also Manufacture of Shoe Polishes, Leather Dressings, etc., p.
6._)


(Pottery, Bricks, Tiles, Glass, etc.)

MODERN BRICKMAKING. By ALFRED B. SEARLE, Royal 8vo. 440
pages. 260 Illustrations. Price 12s. 6d. net. (Post free, 13s. home;
13s. 6d. abroad.)

THE MANUAL OF PRACTICAL POTTING. Compiled by Experts, and Edited by
CHAS. F. BINNS. Third Edition, Revised and Enlarged. 200 pp.
Demy 8vo. Price 17s. 6d. net. (Post free, 17s. 10d. home; 18s. 3d.
abroad.)

POTTERY DECORATING. A Description of all the Processes for Decorating
Pottery and Porcelain. By R. HAINBACH. Translated from the
German. Crown 8vo. 250 pp. Twenty-two Illustrations. Price 7s. 6d. net.
(Post free, 7s. 10d. home; 8s. abroad.)

A TREATISE ON CERAMIC INDUSTRIES. A Complete Manual for Pottery, Tile,
and Brick Manufacturers. By EMILE BOURRY. A Revised Translation
from the French, with some Critical Notes by ALFRED B. SEARLE.
Demy 8vo. 308 Illustrations. 460 pp. Price 12s. 6d. net. (Post free,
13s. home; 13s. 6d. abroad.)

ARCHITECTURAL POTTERY. Bricks, Tiles, Pipes, Enamelled Terra-cottas,
Ordinary and Incrusted Quarries, Stoneware Mosaics, Faïences and
Architectural Stoneware. By LEON LEFÊVRE. Translated from the
French by K.H. BIRD, M.A., and W. MOORE BINNS. With
Five Plates. 950 Illustrations in the Text, and numerous estimates. 500
pp., royal 8vo. Price 15s. net. (Post free, 15s. 6d. home; 16s. 6d.
abroad.)

CERAMIC TECHNOLOGY: Being some Aspects of Technical Science as Applied
to Pottery Manufacture. Edited by CHARLES F. BINNS. 100 pp.
Demy 8vo. Price 12s. 6d. net. (Post free, 12s. 10d. home; 13s. abroad.)

THE ART OF RIVETING GLASS, CHINA AND EARTHENWARE. By J.
HOWARTH. Second Edition. Paper Cover. Price 1s. net. (By post, home
or abroad, 1s. 1d.)

NOTES ON POTTERY CLAYS. The Distribution, Properties, Uses and
Analyses of Ball Clays, China Clays and China Stone. By JAS.
FAIRIE, F.G.S. 132 pp. Crown 8vo. Price 3s. 6d. net. (Post free,
3s. 9d. home; 3s. 10d. abroad.)

HOW TO ANALYSE CLAY. By H.M. ASHBY. Demy 8vo. 72 Pages. 20
Illustrations. Price 3s. 6d. net. (Post free, 3s. 9d. home; 3s. 10d.
abroad.)

A Reissue of

THE HISTORY OF THE STAFFORDSHIRE POTTERIES; AND THE RISE AND PROGRESS
OF THE MANUFACTURE OF POTTERY AND PORCELAIN. With References to Genuine
Specimens, and Notices of Eminent Potters. By SIMEON SHAW.
(Originally published in 1829.) 265 pp. Demy 8vo. Price 5s. net. (Post
free, 5s. 4d. home; 5s. 9d. abroad.)

A Reissue of

THE CHEMISTRY OF THE SEVERAL NATURAL AND ARTIFICIAL HETEROGENEOUS
COMPOUNDS USED IN MANUFACTURING PORCELAIN, GLASS AND POTTERY. By
SIMEON SHAW. (Originally published in 1837.) 750 pp. Royal 8vo.
Price 10s. net. (Post free, 10s. 6d. home; 12s. abroad.)

BRITISH POTTERY MARKS. By G. WOOLLISCROFT RHEAD. Demy 8vo.
310 pp. With over Twelve-hundred Illustrations of Marks. Price 7s. 6d.
net. (Post free, 8s. home; 8s. 3d. abroad.)

_For contents of these books, see List III._


(Glassware, Glass Staining and Painting.)

RECIPES FOR FLINT GLASS MAKING. By a British Glass Master and Mixer.
Sixty Recipes. Being Leaves from the Mixing Book of several experts in
the Flint Glass Trade, containing up-to-date recipes and valuable
information as to Crystal, Demi-crystal and Coloured Glass in its many
varieties. It contains the recipes for cheap metal suited to pressing,
blowing, etc., as well as the most costly crystal and ruby. Second
Edition. Crown 8vo. Price 10s. 6d. net. (Post free, 10s. 9d. home; 10s.
10d. abroad.)

A TREATISE ON THE ART OF GLASS PAINTING. Prefaced with a Review of
Ancient Glass. By ERNEST R. SUFFLING. With One Coloured Plate
and Thirty-seven Illustrations. Demy 8vo. 140 pp. Price 7s. 6d. net.
(Post free, 7s. 10d. home; 8s. abroad.)


(Paper Making, Paper Dyeing, and Testing.)

THE DYEING OF PAPER PULP. A Practical Treatise for the use of
Papermakers, Paperstainers, Students and others. By JULIUS
ERFURT, Manager of a Paper Mill. Translated into English and Edited
with Additions by JULIUS HÜBNER, F.C.S., Lecturer on
Papermaking at the Manchester Municipal Technical School. With
illustrations and 157 patterns of paper dyed in the pulp. Royal 8vo,
180 pp. Price 15s. net. (Post free, 15s. 6d. home; 16s. 6d. abroad).

THE PAPER MILL CHEMIST. By HENRY P. STEVENS, M.A., Ph.D.,
F.I.C. Royal 12mo. 60 illustrations. 300 pp. Price 7s. 6d. net. (Post
free, 7s. 9d. home; 7s. 10d. abroad.)

THE TREATMENT OF PAPER FOR SPECIAL PURPOSES. By L.E. ANDÉS.
Translated from the German. Crown 8vo. 48 Illustrations. 250 pp. Price
6s. net. (Post free, 6s. 4d. home; 6s. 6d. abroad.)


(Enamelling on Metal.)

ENAMELS AND ENAMELLING. For Enamel Makers, Workers in Gold and Silver,
and Manufacturers of Objects of Art. By PAUL RANDAU. Translated
from the German. With Sixteen Illustrations. Demy 8vo. 180 pp. Price
10s. 6d. net. (Post free, 10s. 10d. home; 11s. abroad.)

THE ART OF ENAMELLING ON METAL. By W. NORMAN BROWN.
Twenty-eight Illustrations. Crown 8vo. 60 pp. Price 2s. 6d. net. (Post
free, 2s. 9d. home and abroad.)


(Textile and Dyeing Subjects.)

THE FINISHING OF TEXTILE FABRICS (Woollen, Worsted, Union and other
Cloths). By ROBERTS BEAUMONT, M.Sc., M.I. Mech.E., Professor of
Textile Industries, the University of Leeds; Author of "Colour in Woven
Design"; "Woollen and Worsted Cloth Manufacture"; "Woven Fabrics at the
World's Fair"; Vice-President of the Jury of Award at the Paris
Exhibition, 1900; Inspector of Textile Institutes; Society of Arts
Silver Medallist; Honorary Medallist of the City and Guilds of London
Institute. With 150 Illustrations of Fibres, Yarns and Fabrics, also
Sectional and other Drawings of Finishing Machinery Demy 8vo. 260 pp.
Price 10s. 6d. net. (Post free, 10s. 10d. home; 11s. 3d. abroad.)

FIBRES USED IN TEXTILE AND ALLIED INDUSTRIES. By C. AINSWORTH
MITCHELL, B.A. (Oxon.), F.I.C., and R.M. PRIDEAUX, F.I.C.
With 66 Illustrations specially drawn direct from the Fibres. Demy 8vo.
200 pp. Price 7s. 6d. net. (Post free, 7s. 10d. home; 8s. abroad.)

DRESSINGS AND FINISHINGS FOR TEXTILE FABRICS AND THEIR APPLICATION.
Description of all the Materials used in Dressing Textiles: Their
Special Properties, the preparation of Dressings and their employment in
Finishing Linen, Cotton, Woollen and Silk Fabrics. Fireproof and
Waterproof Dressings, together with the principal machinery employed.
Translated from the Third German Edition of FRIEDRICH POLLEYN.
Demy 8vo. 280 pp. Sixty Illustrations. Price 7s. 6d. net. (Post free,
7s. 10d. home; 8s. abroad.)

THE CHEMICAL TECHNOLOGY OF TEXTILE FIBRES; Their Origin, Structure,
Preparation, Washing, Bleaching, Dyeing, Printing and Dressing. By Dr.
GEORG VON GEORGIEVICS. Translated from the German by
CHARLES SALTER. 320 pp. Forty-seven Illustrations. Royal 8vo.
Price 10s. 6d. net. (Post free, 11s. home; 11s. 3d. abroad.)

POWER-LOOM WEAVING AND YARN NUMBERING, According to Various Systems,
with Conversion Tables. Translated from the German of ANTHON
GRUNER. With Twenty-six Diagrams in Colours. 150 pp. Crown 8vo.
Price 7s. 6d. net. (Post free, 7s. 9d. home; 8s. abroad.)

TEXTILE RAW MATERIALS AND THEIR CONVERSION INTO YARNS. (The Study of
the Raw Materials and the Technology of the Spinning Process.) By
JULIUS ZIPSER. Translated from German by CHARLES
SALTER. 302 Illustrations. 500 pp. Demy 8vo. Price 10s. 6d. net.
(Post free, 11s. home; 11s. 6d. abroad.)

_For contents of these books, see List II_.

GRAMMAR OF TEXTILE DESIGN. By H. NISBET, Weaving and
Designing Master, Bolton Municipal Technical School. Demy 8vo. 280 pp.
490 Illustrations and Diagrams. Price 6s. net. (Post free, 6s. 4d. home;
6s. 6d. abroad.)

ART NEEDLEWORK AND DESIGN. POINT LACE. A Manual of Applied Art for
Secondary Schools and Continuation Classes. By M.E. WILKINSON.
Oblong quarto. With 22 Plates. Bound in Art Linen. Price 3s. 6d. net.
(Post free, 3s. 10d. home; 4s. abroad.)

HOME LACE-MAKING. A Handbook for Teachers and Pupils. By M.E.W.
MILROY. Crown 8vo. 64 pp. With 3 Plates and 9 Diagrams. Price 1s.
net. (Post free, 1s. 3d. home; 1s. 4d. abroad.)

THE CHEMISTRY OF HAT MANUFACTURING. Lectures delivered before the Hat
Manufacturers' Association. By WATSON SMITH, F.C.S., F.I.C.
Revised and Edited by ALBERT SHONK. Crown 8vo. 132 pp. 16
Illustrations. Price 7s. 6d. net. (Post free, 7s. 9d. home; 7s. 10d.
abroad.)

THE TECHNICAL TESTING OF YARNS AND TEXTILE FABRICS. With Reference to
Official Specifications. Translated from the German of Dr. J.
HERZFELD. Second Edition. Sixty-nine Illustrations. 200 pp. Demy
8vo. Price 10s. 6d. net. (Post free, 10s. 10d. home; 11s. abroad.)

DECORATIVE AND FANCY TEXTILE FABRICS. By R.T. LORD. For
Manufacturers and Designers of Carpets, Damask, Dress and all Textile
Fabrics. 200 pp. Demy 8vo. 132 Designs and Illustrations. Price 7s. 6d.
net. (Post free, 7s. 10d. home; 8s. abroad.)

THEORY AND PRACTICE OF DAMASK WEAVING. By H. KINZER and
K. WALTER. Royal 8vo. Eighteen Folding Plates. Six
Illustrations. Translated from the German. 110 pp. Price 8s. 6d. net.
(Post free, 9s. home; 9s. 6d. abroad.)

FAULTS IN THE MANUFACTURE OF WOOLLEN GOODS AND THEIR PREVENTION. By
NICOLAS REISER. Translated from the Second German Edition.
Crown 8vo. Sixty-three Illustrations. 170 pp. Price 5s. net. (Post free,
5s. 4d. home; 5s. 6d. abroad.)

SPINNING AND WEAVING CALCULATIONS, especially relating to Woollens.
From the German of N. REISER. Thirty-four Illustrations.
Tables. 160 pp. Demy 8vo. 1904. Price 10s. 6d. net. (Post free, 10s.
10d. home; 11s. abroad.)

WATERPROOFING OF FABRICS. By Dr. S. MIERZINSKI. Crown 8vo.
104 pp. 29 Illus. Price 5s. net. (Post free, 5s. 3d. home; 5s. 4d.
abroad.)

HOW TO MAKE A WOOLLEN MILL PAY. By JOHN MACKIE. Crown 8vo. 76
pp. Price 3s. 6d. net. (Post free, 3s. 9d. home; 3s. 10d. abroad.)

YARN AND WARP SIZING IN ALL ITS BRANCHES. Translated from the German
of CARL KRETSCHMAR. Royal 8vo. 123 Illustrations. 150 pp. Price
10s. 6d. net. (Post free, 10s. 10d. home; 11s. abroad.)

(_For "Textile Soaps and Oils" see p. 7._)


(Dyeing, Colour Printing, Matching and Dye-stuffs.)

THE COLOUR PRINTING OF CARPET YARNS. Manual for Colour Chemists and
Textile Printers. By DAVID PATERSON, F.C.S. Seventeen
Illustrations. 136 pp. Demy 8vo. Price 7s. 6d. net. (Post free, 7s. 10d.
home; 8s. abroad.)

THE SCIENCE OF COLOUR MIXING. A Manual intended for the use of Dyers,
Calico Printers and Colour Chemists. By DAVID PATERSON, F.C.S.
Forty-one Illustrations. Five Coloured Plates, and Four Plates showing
Eleven Dyed Specimens Of Fabrics. 132 pp. Demy 8vo. Price 7s. 6d. net.
(Post free, 7s. 10d. home; 8s. abroad.)

DYERS' MATERIALS: An Introduction to the Examination, Evaluation and
Application of the most important Substances used in Dyeing, Printing,
Bleaching and Finishing. By PAUL HEERMAN, Ph.D. Translated from
the German by A.C. WRIGHT, M.A. (Oxon)., B.Sc. (Lond.).
Twenty-four Illustrations. Crown 8vo. 150 pp. Price 5s. net. (Post free,
5s. 4d. home; 5s. 6d. abroad.)

COLOUR MATCHING ON TEXTILES. A Manual intended for the use of Students
of Colour Chemistry, Dyeing and Textile Printing. By DAVID
PATERSON, F.C.S. Coloured Frontispiece. Twenty-nine Illustrations
and Fourteen Specimens of Dyed Fabrics. Demy 8vo. 132 pp. Price 7s.
6d. net. (Post free, 7s. 10d. home; 8s. abroad.)

COLOUR: A HANDBOOK OF THE THEORY OF COLOUR. By GEORGE H.
HURST, F.C.S. With Ten Coloured Plates and Seventy-two
Illustrations. 160 pp. Demy 8vo. Price 7s. 6d. net. (Post free, 7s. 10d.
home; 8s. abroad.)

_For contents of these books, see List II_.

Reissue of

THE ART OF DYEING WOOL, SILK AND COTTON. Translated from the French of
M. HELLOT, M. MACQUER and M. LE PILEUR
D'APLIGNY. First Published in English in 1789. Six Plates. Demy
8vo. 446 pp. Price 5s. net. (Post free, 5s. 6d. home; 6s. abroad.)

THE CHEMISTRY OF DYE-STUFFS. By Dr. GEORG VON GEORGIEVICS.
Translated from the Second German Edition. 412 pp. Demy 8vo. Price 10s.
6d. net. (Post free, 11s. home; 11s. 6d. abroad.)

THE DYEING OF COTTON FABRICS: A Practical Handbook for the Dyer and
Student. By FRANKLIN BEECH, Practical Colourist and Chemist.
272 pp. Forty-four Illustrations of Bleaching and Dyeing Machinery. Demy
8vo. Price 7s. 6d. net. (Post free, 7s. 10d. home; 8s. abroad.)

THE DYEING OF WOOLLEN FABRICS. By FRANKLIN BEECH, Practical
Colourist and Chemist. Thirty-three Illustrations. Demy 8vo. 228 pp.
Price 7s. 6d. net. (Post free, 7s. 10d. home; 8s. abroad.)


(Silk Manufacture.)

SILK THROWING AND WASTE SILK SPINNING. By HOLLINS RAYNER.
Demy 8vo. 170 pp. 117 Illus. Price 5s. net. (Post free, 5s. 4d. home;
5s. 6d. abroad.)


(Bleaching and Bleaching Agents.)

A PRACTICAL TREATISE ON THE BLEACHING OF LINEN AND COTTON YARN AND
FABRICS. By L. TAILFER, Chemical and Mechanical Engineer.
Translated from the French by JOHN GEDDES MCINTOSH. Demy 8vo.
303 pp. Twenty Illus. Price 12s. 6d. net. (Post free, 13s. home; 13s.
6d. abroad.)

MODERN BLEACHING AGENTS AND DETERGENTS. By Professor MAX
BOTTLER. Translated from the German. Crown 8vo. 16 Illustrations.
160 pages. Price 5s. net. (Post free, 5s. 3d. home; 5s. 6d. abroad.)


(Cotton Spinning and Combing.)

COTTON SPINNING (First Year). By THOMAS THORNLEY, Spinning
Master, Bolton Technical School. 160 pp. Eighty-four Illustrations.
Crown 8vo. Second Impression. Price 3s. net. (Post free, 3s. 4d. home;
3s. 6d. abroad.)

COTTON SPINNING (Intermediate, or Second Year). By THOMAS
THORNLEY. Second Impression. 180 pp. Seventy Illustrations. Crown
8vo. Price 5s. net. (Post free, 5s. 4d. home: 5s. 6d. abroad.)

COTTON SPINNING (Honours, or Third Year). By THOMAS THORNLEY.
216 pp Seventy-four Illustrations. Crown 8vo. Second Edition. Price 5s.
net. (Post free, 5s. 4d. home; 5s. 6d. abroad.)

COTTON COMBING MACHINES. By THOS. THORNLEY, Spinning Master,
Technical School, Bolton. Demy 8vo. 117 Illustrations. 300 pp. Price 7s.
6d. net. (Post free, 8s. home; 8s. 6d. abroad.)

COTTON WASTE: Its Production, Characteristics, Regulation, Opening,
Carding, Spinning and Weaving. By THOMAS THORNLEY. Demy 8vo.
About 300 pages. [_In the press._

THE RING SPINNING FRAME: GUIDE FOR OVERLOOKERS AND STUDENTS. By N.
BOOTH. Crown 8vo. 76 pages. Price 3s. net. (Post free, 3s. 3d.
home; 3s. 6d. abroad.) [_Just published._


(Flax, Hemp and Jute Spinning.)

MODERN FLAX, HEMP AND JUTE SPINNING AND TWISTING. A Practical Handbook
for the use of Flax, Hemp and Jute Spinners, Thread, Twine and Rope
Makers. By HERBERT R. CARTER, Mill Manager, Textile Expert and
Engineer, Examiner in Flax Spinning to the City and Guilds of London
Institute. Demy 8vo. 1907. With 92 Illustrations. 200 pp. Price 7s. 6d.
net. (Post free, 7s. 9d. home; 8s abroad.)


(Collieries and Mines.)

RECOVERY WORK AFTER PIT FIRES. By ROBERT LAMPRECHT, Mining
Engineer and Manager. Translated from the German. Illustrated by Six
large Plates, containing Seventy-six Illustrations. 175 pp. Demy 8vo.
Price 10s. 6d. net. (Post free, 10s. 10d. home; 11s. abroad.)

VENTILATION IN MINES. By ROBERT WABNER, Mining Engineer.
Translated from the German. Royal 8vo. Thirty Plates and Twenty-two
Illustrations. 240 pp. Price 10s. 6d. net. (Post free, 11s. home; 11s.
3d. abroad.)

HAULAGE AND WINDING APPLIANCES USED IN MINES. By CARL VOLK.
Translated from the German. Royal 8vo. With Six Plates and 148
Illustrations. 150 pp. Price 8s. 6d. net. (Post free, 9s. home; 9s. 3d.
abroad.)

_For contents of these books, see List III._

THE ELECTRICAL EQUIPMENT OF COLLIERIES. By W. GALLOWAY
DUNCAN, Electrical and Mechanical Engineer, Member of the
Institution of Mining Engineers, Head of the Government School of
Engineering, Dacca, India; and DAVID PENMAN, Certificated
Colliery Manager, Lecturer in Mining to Fife County Committee. Demy 8vo.
310 pp. 155 Illustrations and Diagrams. Price 10s. 6d. net. (Post free,
11s. home; 11s. 3d. abroad.)


(Dental Metallurgy.)

DENTAL METALLURGY: MANUAL FOR STUDENTS AND DENTISTS. By A.B.
GRIFFITHS, Ph.D. Demy 8vo. Thirty-six Illustrations. 200 pp. Price
7s. 6d. net. (Post free, 7s. 10d. home; 8s. abroad.)


(Engineering, Smoke Prevention and Metallurgy.)

THE PREVENTION OF SMOKE. Combined with the Economical Combustion of
Fuel. By W.C. POPPLEWELL, M.Sc., A.M. Inst., C.E., Consulting
Engineer. Forty-six Illustrations. 190 pp. Demy 8vo. Price 7s. 6d. net.
(Post free, 7s. 10d. home; 8s. 3d. abroad.)

GAS AND COAL DUST FIRING. A Critical Review of the Various Appliances
Patented in Germany for this purpose since 1885. By ALBERT
PÜTSCH. 130 pp. Demy 8vo. Translated from the German. With 103
Illustrations. Price 5s. net. (Post free, 5s. 4d. home; 5s. 6d. abroad.)

THE HARDENING AND TEMPERING OF STEEL IN THEORY AND PRACTICE. By
FRIDOLIN REISER. Translated from the German of the Third
Edition. Crown 8vo. 120 pp. Price 5s. net. (Post free, 5s. 3d. home; 5s.
4d. abroad.)

SIDEROLOGY: THE SCIENCE OF IRON (The Constitution of Iron Alloys and
Slags). Translated from German of HANNS FREIHERR V. JÜPTNER.
350 pp. Demy 8vo. Eleven Plates and Ten Illustrations. Price 10s. 6d.
net. (Post free, 11s. home; 11s. 6d. abroad.)

EVAPORATING, CONDENSING AND COOLING APPARATUS. Explanations, Formulæ
and Tables for Use in Practice. By E. HAUSBRAND, Engineer.
Translated by A.C. WRIGHT, M.A. (Oxon.), B.Sc., (Lond.). With
Twenty-one Illustrations and Seventy-six Tables. 400 pp. Demy 8vo. Price
10s. 6d. net. (Post free, 11s. home; 11s. 6d. abroad.)


(The "Broadway" Series of Engineering Handbooks.)

VOLUME I.--REINFORCED CONCRETE. By EWART S. ANDREWS,
B.Sc. Eng. (Lond.). [_In the press._

VOLUME II.--GAS AND OIL ENGINES. [_In the press._

VOLUME III.--STRUCTURAL STEEL AND IRON WORK. [_In the press._

VOLUME IV.--TOOTHED GEARING. By G.T. WHITE, B.Sc.
(Lond.). [_In the press._

VOLUME V.--STEAM TURBINES: Their Theory and Construction.
[_In the press._


(Sanitary Plumbing, Electric Wiring, Metal Work, etc.)

EXTERNAL PLUMBING WORK. A Treatise on Lead Work for Roofs. By JOHN
W. HART, R.P.C. 180 Illustrations. 272 pp. Demy 8vo. Second Edition
Revised. Price 7s. 6d. net. (Post free. 7s. 10d. home; 8s. abroad.)

HINTS TO PLUMBERS ON JOINT WIPING, PIPE BENDING AND LEAD BURNING.
Third Edition, Revised and Corrected, By JOHN W. HART, R.P.C.
184 Illustrations. 313 pp. Demy 8vo. Price 7s. 6d. net. (Post free, 8s.
home; 8s. 6d. abroad.)

SANITARY PLUMBING AND DRAINAGE. By JOHN W. HART. Demy 8vo.
With 208 Illustrations. 250 pp. 1904. Price 7s. 6d. net. (Post free, 7s.
10d. home; 8s. abroad.)

ELECTRIC WIRING AND FITTING. By SYDNEY F. WALKER, R.N.,
M.I.E.E., M.I.Min.E., A.M.Inst.C.E., etc., etc. Crown 8vo. 150 pp. With
Illustrations and Tables. Price 5s. net. (Post free, 5s. 3d. home; 5s.
6d. abroad.)

THE PRINCIPLES AND PRACTICE OF DIPPING, BURNISHING, LACQUERING AND
BRONZING BRASS WARE. By W. NORMAN BROWN. 48 pp. Crown 8vo.
Price 3s. net. (Post free, 3s. 3d. home and abroad.) [_Just published._

THE DEVELOPMENT OF THE INCANDESCENT ELECTRIC LAMPS. By G. BASIL
BARHAM, A.M.I.E.E. Illustrated. Demy 8vo. 196 pp. [_In the press._

_For contents of these books, see List I._

WIRING CALCULATIONS FOR ELECTRIC LIGHT AND POWER INSTALLATIONS. A
Practical Handbook containing Wiring Tables, Rules, and Formulæ for the
Use of Architects, Engineers, Mining Engineers, and Electricians, Wiring
Contractors and Wiremen, etc. By G. LUMMIS PATERSON. Crown 8vo.
Twenty-two Illustrations. 100 pp. [_In the press._

A HANDBOOK ON JAPANNING AND ENAMELLING FOR CYCLES, BEDSTEADS, TINWARE,
ETC. By WILLIAM NORMAN BROWN. 52 pp. and Illustrations. Crown
8vo. Price 2s. net. (Post free, 2s. 3d. home and abroad.)

THE PRINCIPLES OF HOT WATER SUPPLY. By JOHN W. HART, R.P.C.
With 129 Illustrations. 177 pp. Demy 8vo. Price 7s. 6d. net. (Post free,
7s. 10d. home; 8s. abroad.)


(Brewing and Botanical.)

HOPS IN THEIR BOTANICAL, AGRICULTURAL AND TECHNICAL ASPECT, AND AS AN
ARTICLE OF COMMERCE. By EMMANUEL GROSS, Professor at the
Higher Agricultural College, Tetschen-Liebwerd. Translated from the
German. Seventy-eight Illustrations. 340 pp. Demy 8vo. Price 10s. 6d.
net. (Post free, 11s. home; 11s 6d. abroad.)

A BOOK ON THE DISEASES OF PLANTS, FUNGICIDES AND INSECTICIDES, ETC.
Demy 8vo. About 500 pp. [_In the press._


(Wood Products, Timber and Wood Waste.)

WOOD PRODUCTS: DISTILLATES AND EXTRACTS. By P. DUMESNY,
Chemical Engineer, Expert before the Lyons Commercial Tribunal, Member
of the International Association of Leather Chemists; and J.
NOYER. Translated from the French by DONALD GRANT. Royal
8vo. 320 pp. 103 Illustrations and Numerous Tables. Price 10s. 6d. net.
(Post free, 11s. home; 11s. 6d. abroad.)

TIMBER: A Comprehensive Study of Wood in all its Aspects (Commercial
and Botanical), showing the different Applications and Uses of Timber in
Various Trades, etc. Translated from the French of PAUL
CHARPENTIER. Royal 8vo. 437 pp. 178 Illustrations. Price 12s. 6d.
net. (Post free, 13s. home; 14s. abroad.)

THE UTILISATION OF WOOD WASTE. Translated from the German of ERNST
HUBBARD. Crown 8vo. 192 pp. Fifty Illustrations. Price 5s. net.
(Post free, 5s. 4d. home; 5s. _6d_. abroad.)

(_See also Utilisation of Waste Products, p. 9._)


(Building and Architecture.)

ORNAMENTAL CEMENT WORK. By OLIVER WHEATLEY. Demy 8vo. 83
Illustrations. 128 pp. Price 5s. net. (Post free, 5s. 4d. home; 5s. 6d.
abroad.) [_Just published._

THE PREVENTION OF DAMPNESS IN BUILDINGS; with Remarks on the Causes,
Nature and Effects of Saline, Efflorescences and Dry-rot, for
Architects, Builders, Overseers, Plasterers, Painters and House Owners.
By ADOLF WILHELM KEIM. Translated from the German of the second
revised Edition by M.J. SALTER, F.I.C., F.C.S. Eight Coloured
Plates and Thirteen Illustrations. Crown 8vo. 115 pp. Price 5s. net.
(Post free, 5s. 3d. home; 5s. 4d. abroad.)

HANDBOOK OF TECHNICAL TERMS USED IN ARCHITECTURE AND BUILDING, AND
THEIR ALLIED TRADES AND SUBJECTS. By AUGUSTINE C. PASSMORE.
Demy 8vo. 380 pp. Price 7s. 6d. net. (Post free, 8s. home; 8s. 6d.
abroad.)


(Foods, Drugs and Sweetmeats.)

FOOD AND DRUGS. By E.J. PARRY, B.Sc., F.I.C., F.C.S. Volume
I. The Analysis of Food and Drugs (Chemical and Microscopical). Royal
8vo. 724 pp. Price 21s. net. (Post free, 21s. 8d. home; 22s. abroad.)
Volume II. The Sale of Food and Drugs Acts, 1875-1907. Royal 8vo. 184
pp. Price 7s. 6d. net. (Post free, 7s. 10d. home; 8s. abroad.) [_Just
published._

THE MANUFACTURE OF PRESERVED FOODS AND SWEETMEATS. By A.
HAUSNER. With Twenty-eight Illustrations. Translated from the
German of the third enlarged Edition. Crown 8vo. 225 pp. Price 7s. 6d.
net. (Post free, 7s. 9d. home; 7s. 10d. abroad.)

RECIPES FOR THE PRESERVING OF FRUIT, VEGETABLES AND MEAT. By E.
WAGNER. Translated from the German. Crown 8vo. 125 pp. With 14
Illustrations. Price 5s. net. (Post free, 5s. 3d. home; 5s. 4d. abroad.)

_For contents of these books, see List III._


(Dyeing Fancy Goods.)

THE ART OF DYEING AND STAINING MARBLE, ARTIFICIAL STONE, BONE, HORN,
IVORY AND WOOD, AND OF IMITATING ALL SORTS OF WOOD. A Practical
Handbook for the Use of Joiners, Turners, Manufacturers of Fancy Goods,
Stick and Umbrella Makers, Comb Makers, etc. Translated from the German
of D.H. SOXHLET, Technical Chemist. Crown 8vo. 168 pp. Price
5s. net. (Post free, 5s. 3d. home; 5s. 4d. abroad.)


(Celluloid.)

CELLULOID: Its Raw Material, Manufacture, Properties and Uses. A
Handbook for Manufacturers of Celluloid and Celluloid Articles, and all
Industries using Celluloid; also for Dentists and Teeth Specialists. By
Dr. Fr. BÖCKMANN, Technical Chemist. Translated from the Third
Revised German Edition. Crown 8vo. 120 pp. With 49 Illustrations. Price
5s. net. (Post free, 5s. 3d. home; 5s. 4d. abroad.)


(Lithography, Printing and Engraving.)

PRACTICAL LITHOGRAPHY. By ALFRED SEYMOUR. Demy 8vo. With
Frontispiece and 33 Illus. 120 pp. Price 5s. net. (Post free, 5s. 4d.
home; 5s. 6d. abroad.)

PRINTERS' AND STATIONERS' READY RECKONER AND COMPENDIUM. Compiled by
VICTOR GRAHAM. Crown 8vo. 112 pp. 1904. Price 3s. 6d. net.
(Post free, 3s. 9d. home; 3s. 10d. abroad.)

ENGRAVING FOR ILLUSTRATION. HISTORICAL AND PRACTICAL NOTES. By J.
KIRKBRIDE. 72 pp. Two Plates and 6 Illustrations. Crown 8vo. Price
2s. 6d. net. (Post free, 2s. 9d. home; 2s. 10d. abroad.)

(_For Printing Inks, see p. 4._)


(Bookbinding.)

PRACTICAL BOOKBINDING. By PAUL ADAM. Translated from the
German. Crown 8vo. 180 pp. 127 Illustrations. Price 5s. net. (Post free,
5s. 4d. home; 5s. 6d. abroad.)


(Sugar Refining.)

THE TECHNOLOGY OF SUGAR: Practical Treatise on the Modern Methods of
Manufacture of Sugar from the Sugar Cane and Sugar Beet. By JOHN
GEDDES MCINTOSH. Second Revised and Enlarged Edition. Demy 8vo.
Fully Illustrated. 436 pp. Seventy-six Tables. 1906. Price 10s. 6d. net.
(Post free, 11s. home; 11s. 6d. abroad.)

(_See "Evaporating, Condensing, etc., Apparatus," p. 9._)


(Emery.)

EMERY AND THE EMERY INDUSTRY. Translated from the German of A.
HAENIG. Crown 8vo. 45 Illustrations. 110 pp. Price 5s. net. (Post
free, 5s. 3d. home; 5s. 6d. abroad.) [_Just published._


(Libraries and Bibliography.)

CLASSIFIED GUIDE TO TECHNICAL AND COMMERCIAL BOOKS. Compiled by
EDGAR GREENWOOD. Demy 8vo. 224 pp. 1904. Being a Subject-list
of the Principal British and American Books in Print; giving Title,
Author, Size, Date, Publisher and Price. Price 5s. net. (Post free, 5s.
4d. home; 5s. 6d. abroad.)

HANDBOOK TO THE TECHNICAL AND ART SCHOOLS AND COLLEGES OF THE UNITED
KINGDOM. Containing particulars of nearly 1,000 Technical, Commercial
and Art Schools throughout the United Kingdom. With full particulars of
the courses of instruction, names of principals, secretaries, etc. Demy
8vo. 150 pp. Price 3s. 6d. net. (Post free, 3s. 10d. home; 4s. abroad.)

THE LIBRARIES, MUSEUMS AND ART GALLERIES YEAR BOOK, 1910-11. Being the
Third Edition of Greenwood's "British Library Year Book". Edited by
ALEX. J. PHILIP. Demy 8vo. 286 pp. Price 5s. net. (Post free,
5s. 4d. home; 5s. 6d. abroad.)

THE PLUMBING, HEATING AND LIGHTING ANNUAL FOR 1911. The Trade
Reference Book for Plumbers, Sanitary, Heating and Lighting Engineers,
Builders' Merchants, Contractors and Architects. Quarto. Bound in cloth
and gilt lettered. Price 3s. net. (Post free, 3s. 4d. home; 3s. 8d.
abroad.)

_Including the translation of Hermann Kechnagel's "Kalender fur
Gesundheits-Techniker," Handbook for Heating, Ventilating, and Domestic
Engineers, of which Scott, Greenwood & Son have purchased the sole right
for the English Language._


SCOTT, GREENWOOD & SON,
_Technical Book and Trade Journal Publishers_,
8 BROADWAY, LUDGATE HILL,
LONDON, E.C.

Telegraphic Address, "Printeries, London". Tel. No.: Bank 5403.
_January, 1912_.





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