Scientific American Supplement, No. 286, June 25, 1881 by Various
page 34 of 115 (29%)
page 34 of 115 (29%)
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THE CONSTITUENT PARTS OF LEATHER. The constituent parts of leather seem to be but little understood. The opinions of those engaged in the manufacture of leather differ widely on this question. Some think that tannin assimilates itself with the hide and becomes fixed there by reason of a special affinity. Others regard the hide as a chemical combination of gelatine and tannin. We know that the hide contains some matters which are not ineradicable, but only need a slight washing to detach them. We deem it advisable, in order to examine the hide properly so-called, to dispense with those eradicable substances which may be regarded, to some extent, as not germain to it, and confine our attention to the raw stock, freed from these imperfections. It is well known that a large number of vegetable substances are employed as tanning agents. Our researches have been directed to leather tanned by means of the most important of these agents. Many questions present themselves in the course of such an examination. Among others, that most important one, from a practical point of view, of the weight the tanning agent gives to the hide, that is to say, the result in leather of weight given to the raw material. The degree of tannage is also to be considered; the length of time during which the tanning agent is to be left with the hide; in short, the influence upon |
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