Part 1 (1/2)
The Che
by Watson Smith
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, FRS, then the Professor of Chee, Manchester, and he advised the formation of an association, and the appointation 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 recoy in the Owens College, as lecturer, and he was accordingly appointed
The lectures were delivered with copious experi 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 es 66-68)
This reive 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 the as their only resource In a letter recently received froree with you that this is a good instance of the _direct , and in these days of 'protection' and sies, it is not a to the writer to think that the lectures have had soress 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
LECTURE I
TEXTILE FIBRES, PRINcipaLLY WOOL, FUR, AND HAIR
_Vegetable Fibres_--Textile fibres etable and animal fibres It is absolutely necessary, in order to obtain a useful knowledge of the peculiarities and properties of anienerally, or even specially, that we should be, at least to soetable fibres I shall therefore have, in the first place, soetable fibres before we commence theto you as hat manufacturers, naetable 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,1) We know it is a tube, because on taking a thin, narrow slice across a fibre and exa the slice under the microscope, we can see the hole or perforation up the centre, for 2)
Mr H de Mosenthal, in an extre and valuable paper (see _JSCI_,[1] 1904, vol xxiii p 292), has recently shown that the cuticle of the cotton fibre is extre, in addition to pores, what appear to be ed in oblique rows, as if they led into oblique lateral channels
A cotton fibre varies froth, and in breadth from 0017 to 005 millimetre The characteristics uish cotton froetable fibre is flax, or linen, and this has a very different appearance under the3) 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 naiven 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 sorows freely in the German colony called the Camaroons, and also on the Gold Coast This fibre, under the microscope, differs entirely in appearance froht and thin, se 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 _JSCI_, 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 che to the relative proportions of these constituents, it has had the chened 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 colucose It is possible to convert cotton rags into this for vitriol or sulphuric acid, and then boiling with dilute acid for a long tietable or cellulose fibres, I will give you a uish thest which are silk, wool, fur, and hair A good general test to distinguish a vegetable and an ani, which is known as Molisch's test: To a very sram, of the ashed cotton fibre, 1 cc
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 anireenish-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 terated 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 lih 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, e that froetable fibre under like circuood test is to burn a piece of the fibre in a laetable 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 etable fibres, if kept out of contact with the air, the animal fibres are very quickly attacked Superheated steaetable fibres, but it would fuse or melt wool Based on these differences,as, or , 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 botto (Heddebault) If rite 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 frooods bycotton, 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 15, _ie_ 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 a acids to the cupric-ammoniuelatinous mass Cotton and linen are scarcely dissolved at all by a solution of basic zinc chloride
[Footnote 1: _JSCI = 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 ulands placed on the side of the body of the silk-wor 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 lassy surface There is, however, a longitudinal groove of more or less depth The fibre is se due to the sht In the silk fibre there are two distinct parts: first, the central portion, or, as we ard it, the true fibre, chemically termed _fibron_; and secondly, an envelope composed of a substance or substances, cheum” Both the latter and _fibron_ are coen
Here there is thus one eleetable fibres previously referred to, naen is contained in all the anilue or sericin can be dissolved off the inner fibron fibre by means of hot water, or ater 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 unguhtly attacks silk, and colours it yellow; it would not so colour vegetable fibres, and this foretable fibre Cold strong acetic acid, so-called glacial acetic acid, re u under pressure with acetic acid, however, silk is co sulphuric acid, for a brown thick liquid If we add water to this thick liquid, a clear solution is obtained, and then on adding tannic acid the fibron 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 fibron; but they are not so good for ungu 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