The Chemistry of Hat Manufacturing | Page 7

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