Butler citizen. [volume] (Butler, Pa.) 1877-1922, 1880-03-10
SCIENCE AS APPLIED TO
AIMING.

IANNING.
Considering the immensity of the
trade, modern science has done but
little for the tanning industry. Except
in the perfecting of few compare
lively simple mechanical devices for
the saving of labor, the work of tam
ming heavy leather is row very nearly
the same as it was hundred years
ago. The time required for tanning
has been shortened by the use of
stronger bark solutions, and more fre-
quent handling of the hide or skin in
such liquor but the principle is the
same; greater variety of tanning
agents are employed, the astringent
principle, similar to that found in oak
bark, and which exists in greater or
less proportions in almost every plant,
must be sufficient to combine with the
gelatine of the hide, which alone
makes tanned or tawed leather.
Yet there has been no lack of en-
deavor in this field, for substantial,
or even partial success, in the making
of something which would compete
with an article so universally used as
leather, or in perfecting a cheaper
mode of producing it, would be sure
to bring to the discoverer or inventor
large rewards German chemists have
been especially active in this direction
One of them has claimed that tanning
is not, as it has always heretofore been
considered, chemical operation, but
that it is simply mechanical, and that
the tanning only surrounds, but does
not actually combine with the particles
of gelatine. This theory has not met
with general acceptance, but it is,
nevertheless, certain that leather
tanned with some description of tan
ming material, such as valonia, gam
bier, and divi-divi, can be again so far
brought back to the raw hide condi-
tion as to be suitable for use in the
making of glue The most noteworthy
result of the recent efforts of German
chemists has been, however, in the
perfection of q method of making
leather without the use of bark at all,
by what is called mineral tanning,
with a solution principally of iron,
making what is called an iron canned
leather Some very fair samples of
both upper and sole leather have been
produced by this process, and it is
claimed that leather can be made
thereby in much less time than it
takes by the old method, and with
material saving of cost 1t is to be
remarked, however, that the sole
leather so made is very hard and brit
tie, so that it is difficult to make up
and finish in q boot or shoe, and is
liable to chip out and wear away rap
idly except in wet weather 1t seems,
however, to have sufficient toughness,
when wet, to resist good amount of
wear, and its water resisting qualities
are about equal to those of many
kinds of bark tanned leather. That
it will, as at present made, come into
competition with our leather, does not
appear at all likely. but the fact that
hides and skins are now chemically
treated so as to make an article nearly
resembling bark tanned leather, and
which will make serviceable boots and
shoes, marks step forward in the
progress of an industry, which, though
one of the oldest in the world, has
probably shown less change than any
other.
The German process above alluded
to has been covered by two patents in
this country, but no leather of such
manufacture has yet been made here.
In fact the process can hardly be said
to have met with any decided favor in
Germany, where, from the high price
of tanning material, and the general
inferior quality of sole leather man.
ufactured, it would seem to have most
chance of being adopted. The patents
cover the process, and new chemical
compound, as mineral reagent, in the
place of vegetable tanning material.
The process includes the making of
peculiarly prepared basic sulphate of
iron, which forms the tanning ma
terial into which the hides or skins are
placed for two or at the most four
DAYS, without any handling or chang
ing liquors. 1t is this part of the pro-
cess of making leather in the ordinary
way which requires so much time and
labor, heavy hides being kept in the
bark liquors from two to six or seven
months, and in some cases consider
ably longer The preparation of the
hide for the liquor or compound, SO
far as the removal of the hair, flesh,
etc, are concerned, is supposed to be
| the same for the new tanning process
as by the old method of tanning, as
are also the currying and finishing
operations
We can now make very cheap
leather in this country, becarse bark
is so abundant, and the iron tanned
leather has not as yet been brought to
such a standard of excellence that it
can compete with the product which
our native forests supply US with the
means of furnishing; but it requires
no long look into the future to see that
these conditions may, at no very as
tant day. be reversed. Our woods
are being rapidly destroyed, so that
available bark for tanning is found,
year bv year, only at a greater dis
tance, and this will afford additional
incentives to a spirit of investigation
and research which may, in time, find
US substitute for bark in the manu-
facture of leather.-Scieptifc Ameri-
can.