Year: 1886

page_text: I, PERCY. HADDAN of the firm of Herbert & Co Patent Agents, of 67 Strand in
tho County of Middlesex, Civil Engineer, do hereby declare the nature of this
invention, a communication to me from abroad by The Dobson Patent Tanning
Process Company, of Lincoln, State of Nebraska, United States, and in what
manner the same is to be performed to be particularly described and ascertained
in and by the following statement:-
In practice it has been found that instead of subjecting the hides (after prepara-
tion in the usual way) to a bath of tanning extract and salt water, and next to the
fumes of sulphur, it is far better to first subject them to the action of a bath of
chloride of sodium, in other words, salt water or brine, and next to the sulphur
fumes, and afterwards to a bath of the tanning extract or coloring liquor, and
finally again to the action of the sulphur fumes; the leather produced by the
improved process being much stronger, more pliable and durable, than "bark
tanned leather" and better in several respects, than the leather produced by the
process set forth above. Furthermore, by the new and improved process, leather
can be treated at about half the cost of that usually required for the production of
bark-tanned leather.
'
The ordinary process of producing bark-tanned leather includes one operation
termed "baiting" which is not only for neutralizing the lime absorbed by the hides
in the unhairing process, but for rotting or destroying the gelatinous matter in
them. This baiting process besides being disagreeable, laborious and expensive is
apt to distend and weaken the fibres of the hides, and at certain times before the
tanning process is completed, to render them liable to be injuriously affected by
ozone in the atmosphere, especially during a thunder storm, or when the air is
surcharged with electricity. I have discovered, that the baiting process may be
dispensed with preparatory to the tanning of the hides, and that the subjection of
them to a bath of chloride of sodium, or to strong salt water or brine, and next to
the fumes of burning sulphur, may be substituted, whereby they are left uninjured,
and the strength of their fibres is unimpaired, and their pliability is improved, the
dirty and offensive work of the baiting process as well as much of the labor incident
thereto, being thereby avoided.

page_text: Experience has demonstrated, that when hides, before being bark tanned, are
treated by a bath of salt water, and next fumigated, as mentioned, they are in a
much better condition for the absorption and retention of the tanning material,
than they are after being treated by the baiting process, and that they can be
thoroughly tanned with very much less material and in a much shorter time, and
besides are generally softer, stronger, better in color, and more durable.
The action of the salt, or chloride of sodium, and the sulphurous fumes or gas
upon the gelatine of the hides appears to be such as to decompose it or entirely
change its character, without producing putrefaction of it, it being left in and not
materially extracted from the hides. After thus treating the hides or skins, they
may be tanned, curried and finished in the usual way.
So hides, at any stage of tanning them may generally, if not always be improved
by subjecting them to a bath of brine and subsequently to the action of fumes of
burning sulphur.
T
In treating the skins or hides, I proceed as follows:
First unhair them in the usual way, and next wash them in a wheel or other-
wise, for about half an hour, in cold water. After which, the fine or remaining hair,
if any is to be removed from them and they are to be immersed for from 24 to 36
hours in a bath of salt water, or brine, in strength usually about 9 to 11 degrees
Salinometer, they being handled once in the meantime. Next they are to be
subjected to the fumes of burning sulphur, good judgment being used as to the size
of the compartment, in which they may be placed for being fumigated, and the
amount of the gas to which they may be exposed. I usually use a room
about sixteen feet square and nine feet in height and having apertures for the
admission of a proper amount of air for keeping up the combustion of the sulphur.
A charge of eight to ten pounds of sulphur in two or more iron pots or vessels gives
better results than in one single pot, such being sufficient for one hundred and sixty
heavy sides, or two hundred, to two hundred and forty light sides, of forty to fifty
pounds hides.
.
The hides are to be suitably suspended in the apartment, for the sulphurous
fumes to thoroughly gain access to them and generally remain from. twelve to
fourteen hours. After removal of the hides from the fumigating apartment, they
are ready for the coloring or tanning bath, in the making of which I generally use
for forty sides, about one hundred and twenty pounds of gambier, about two
hundred pounds of salt and fifteen pounds of alum. The liquor, with the hides,
I put in a wheel or suitable vat, and subject them to its action for about twenty-
four hours. The strength of the liquor may be about 11 to 12 Tannometer, and 9
to 11 of the Salinometer. After one pack of the hides have been removed from the
vat, the liquor 'therein may be strengthened for another pack by the addition of
about half a pound of gambier to each side; and eight to ten pounds of alum
for all of them:
,
The hides after having thus been treated and brought into a suitable condition,
are to be skived and split The grain portion I usually afterwards put into gambier
liquor, and the other or flesh portion into hemlock liquor for twelve. to twentyfour
hours. The flesh portion will then be ready for being dried and for sale or use.
The grain portion I generally next subject to the action of sulphur fumes for about
twelve hours and afterwards wash it. Having "slicked it off" on the grain'side, it
will be ready for being stuffed with grease or oil, which may be accomplished by
means of a stuffing wheel as used by tanners. It subsequently may be finished as
leather usually is after being stuffed."
Having now particularly described and ascertained the nature of this inven
tion and, in what manner the same is to be performed, I declare that what
I claim is:
=
T
0
1.) The improved process substantially as hereinbefore described, of treating the
hides, it consisting in subjecting them to the action of a bath of salt water or bring

page_text: next to fumes of burning sulphur, next to a bath of tanning extract or coloring
liquor, and afterwards to fumes of burning sulphur, all essentially as specified.
2.) Subjecting the hides to a bath of strong salt water or brine, next to fumes of
burning sulphur, and afterwards tanning them by a solution of tanning extract or
a decoction of bark or other proper tanning extract, all being substantially as
specified.
3.) Subjecting hides in the process of tanning them to the action of a bath of
brine or common salt, and next exposing them to contact with the fumes of
burning sulphur, all being essentially as set forth.
4.) Subjecting hides or skins to a bath of common salt, or chloride of sodium, and
exposing them to the fumes of burning sulphur without subjecting them to a
solution of tanning extract.