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