Year: 1886

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I, HENRY HARRIS LAKE, of the firm of Haseltine, Lake & Co. Patent Agents,
Southampton Buildings, in the County of Middlesex, do hereby declare the
nature of this invention and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement:-
This invention has for its chief object to enable the tanning. of hides and skins
to be effected more rapidly than heretofore.
According to the said invention I effect the tanning in a pit of the ordinary or
any other suitable construction, but in order to accelerate the operation I inject
air at the bottom of each pit through a pipe connected with a rotary or other
pump or fan capable of forcing air. This air sets in motion the mass, composed of
powdered bark, tannic extracts and water, which forms the tanning liquor. This
tanning liquor can be prepared previous to its introduction into the pit.
My said invention is illustrated in the accompanying drawing in which,
Figure 1 is a plan view shewing the arrangement of apparatus for carrying my
process into practice, and
Figure 2 is a central vertical section of the said apparatus.
The hides or skins to be tanned are suspended from bars D placed at the upper
part of the tan pit E, which can be hermetically closed by means of a hinged
cover G or a hydraulic joint, or by any other suitable means.
A rotary pump or fan B forces air through the pipe A to the bottom of the tan
pit. The air forced into the liquid by this pump can be drawn from the pit
through the pipe F so that it is more or less charged with tannic principles, or it
can be wholly or partially drawn from the external atmosphere through the pipe C.
A cock J is provided by means of which the introduction of air from the upper
part of the pit or from the external atmosphere can be regulated.
The funnel H serves to introduce water and tannic principles into the pit.
Instead of placing the substances from which the tanning liquor is formed in
the pit with the hides or skins the said tanning liquor can be prepared separately.
For this purpose I place the water and the tanning substances in a vat which
can be closed, if desired, and we introduce a current of air at the bottom of this
D

page_text: vat to effect the maceration and dissolution of the bark and tanning. The sub-
stances can be stirred by the air either in a continuous manner or at intervals.
When the liquors are thus prepared they are poured into the pit in which the
hides are suspended as described and the tanning is then commenced, air being
caused to enter continually at the bottom of the pit.
The tanning liquors can be prepared either with pulverized bark or with pieces.
or chips of wood containing tannic principles.
The liquors can be of any desired degree of concentration.
According to circumstances I can, as already stated inject at the bottom of the
vat either the air or vapour alone which is drawn from the upper part of the pit
through the pipe F, or air mixed in variable proportions with external air drawn
through the pipe C or external air alone.
The stirring or agitating of the liquor by air, as described produces excellent
results in the tanning, and the liquors are perfectly clear.
It might have been supposed that the air would give rise to oxidation capable
of producing gallic acid which would have blackened the hides; but this result is
not produced, the liquors on the contrary being purified.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed as communicated to
me by my foreign correspondents I declare that what I claim is ;-
The process of rapidly tanning hides (and of preparing tanning liquors if desired)
which consists in causing air drawn from the upper part of the tan pit either alone
or mixed with external air, or external air alone, to enter at the lower part of the
said pit this air being introduced by means of a rotary pump, a fan or by any
other suitable means.