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diff --git a/17740-8.txt b/17740-8.txt new file mode 100644 index 0000000..0c418d8 --- /dev/null +++ b/17740-8.txt @@ -0,0 +1,5722 @@ +Project Gutenberg's The Chemistry of Hat Manufacturing, by Watson Smith + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: The Chemistry of Hat Manufacturing + Lectures Delivered Before the Hat Manufacturers' Association + +Author: Watson Smith + +Editor: Albert Shonk + +Release Date: February 10, 2006 [EBook #17740] + +Language: English + +Character set encoding: ISO-8859-1 + +*** START OF THIS PROJECT GUTENBERG EBOOK THE CHEMISTRY OF HAT MANUFACTURING *** + + + + +Produced by Jason Isbell, Josephine Paolucci and the Online +Distributed Proofreading Team at http://www.pgdp.net + + + + + + + + + + + + +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 +PAINTS, COLOURS, VARNISHES AND ALLIED PREPARATIONS. By GEORGE H. +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 +Recipes given in the Book. 136 pp. Demy 8vo. Price 7s. 6d. net. (Post +free, 7s. 10d. home; 8s. abroad.) + +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 +free, 13s. home; 13s. 6d. abroad.) + +RECIPES FOR THE COLOUR, PAINT, VARNISH, OIL, SOAP AND DRYSALTERY +TRADES. Compiled by AN ANALYTICAL CHEMIST. 350 pp. Second +Revised Edition. Demy 8vo. Price 10s. 6d. net. (Post free, 11s. home; +11s. 3d. abroad.) + +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 +Manufacturers and Printers. By ALFRED SEYMOUR. Demy 8vo. Six +Illustrations. 90 pages. Price 5s. net. (Post free, 5s. 4d. home; 5s. +6d. abroad.) + +THREE HUNDRED SHADES AND HOW TO MIX THEM. For Architects, Painters and +Decorators. By A. DESAINT, Artistic Interior Decorator of +Paris. The book contains 100 folio Plates, measuring 12 in. by 7 in., +each Plate containing specimens of three artistic shades. These shades +are all numbered, and their composition and particulars for mixing are +fully given at the beginning of the book. Each Plate is interleaved with +grease-proof paper, and the volume is very artistically bound in art and +linen with the Shield of the Painters' Guild impressed on the cover in +gold and silver. Price 21s. net. (Post free, 21s. 6d. home; 22s. 6d. +abroad.) + +HOUSE DECORATING AND PAINTING. By W. NORMAN BROWN. +Eighty-eight Illustrations. 150 pp. Crown 8vo. Price 3s. 6d. net. (Post +free, 3s. 9d. home and abroad.) + +A HISTORY OF DECORATIVE ART. By W. NORMAN BROWN. Thirty-nine +Illustrations. 96 pp. Crown 8vo. Price 1s. net. (Post free, 1s. 3d. home +and abroad.) + +WORKSHOP WRINKLES. for Decorators, Painters, Paperhangers, and Others. +By W.N. BROWN. Crown 8vo. 128 pp. Second Edition. Price 2s. 6d. +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 +Edition. 160 pp. Price 7s. 6d. net. (Post free, 7s. 10d. home; 8s. +abroad.) + +SIMPLE METHODS FOR TESTING PAINTERS' MATERIALS. By A.C. +WRIGHT, M.A. (Oxon.)., B.Sc. (Lond.). Crown 8vo. 160 pp. Price 5s. +net. (Post free, 5s. 3d. home; 5s. 6d. abroad.) + +IRON-CORROSION, ANTI-FOULING AND ANTI-CORROSIVE PAINTS. Translated +from the German of LOUIS EDGAR ANDÉS. Sixty-two Illustrations. +275 pp. Demy 8vo. Price 10s. 6d. net. (Post free, 10s. 10d. home; 11s. +3d. abroad.) + +THE TESTING AND VALUATION OF RAW MATERIALS USED IN PAINT AND COLOUR +MANUFACTURE. By M.W. JONES, F.C.S. A Book for the Laboratories +of Colour Works. 88 pp. Crown 8vo. Price 5s. net. (Post free, 5s. 3d. +home and abroad.) + +_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. +4d. abroad.) + +STUDENTS' HANDBOOK OF PAINTS, COLOURS, OILS AND VARNISHES. By JOHN +FURNELL. Crown 8vo. 12 Illustrations. 96 pp. Price 2s. 6d. net. +(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. +(Post free, 7s. 10d. home; 8s. abroad.) + +VOLUME II.--VARNISH MATERIALS AND OIL-VARNISH MAKING. Demy +8vo. 70 Illustrations. 220 pp. Price 10s. 6d. net. (Post free, 10s. 10d. +home; 11s. 3d. abroad.) + +VOLUME III.--SPIRIT VARNISHES AND SPIRIT VARNISH MATERIALS. +Demy 8vo. Illustrated. 464 pp. Price 12s. 6d. net. (Post free, 13s. +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 +Illustrations. Price 6s. net. (Post free, 6s. 4d. home; 6s. 6d. abroad.) + +THE PRACTICAL COMPOUNDING OF OILS, TALLOW AND GREASE FOR LUBRICATION, +ETC. By An EXPERT OIL REFINER. Second Edition. 100 pp. Demy +8vo. Price 7s. 6d. net. (Post free, 7s. 10d. home; 8s. abroad.) + +THE MANUFACTURE OF LUBRICANTS, SHOE POLISHES AND LEATHER DRESSINGS. By +RICHARD BRUNNER. Translated from the Sixth German Edition by +CHAS. SALTER. 10 Illustrations. Crown 8vo. 170 pp. Price 7s. +6d. net. (Post free, 7s. 10d. home; 8s. abroad.) + +THE OIL MERCHANTS' MANUAL AND OIL TRADE READY RECKONER. Compiled by +FRANK F. SHERRIFF. Second Edition Revised and Enlarged. Demy +8vo. 214 pp. With Two Sheets of Tables. Price 7s. 6d. net. (Post free, +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. 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(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_. + + + + + +End of Project Gutenberg's The Chemistry of Hat Manufacturing, by Watson Smith + +*** END OF THIS PROJECT GUTENBERG EBOOK THE CHEMISTRY OF HAT MANUFACTURING *** + +***** This file should be named 17740-8.txt or 17740-8.zip ***** +This and all associated files of various formats will be found in: + http://www.gutenberg.org/1/7/7/4/17740/ + +Produced by Jason Isbell, Josephine Paolucci and the Online +Distributed Proofreading Team at http://www.pgdp.net + + +Updated editions will replace the previous one--the old editions +will be renamed. + +Creating the works from public domain print editions means that no +one owns a United States copyright in these works, so the Foundation +(and you!) can copy and distribute it in the United States without +permission and without paying copyright royalties. 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