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