IMPROVEMENTS IN PREPARING AND TANNING HIDES AND SKINS
Year: 1855

page_text: PROVISIONAL SPECIFICATION left by François Devos at the Office of
the Commissioners of Patents, with his Petition, on the 8th December
1855.
I, FRANÇOIS DEVOS, of 2, Rue Drouot, Paris, do hereby declare the nature
of the Invention for "IMPROVEMENTS IN PREPARING AND TANNING HIDES AND
SKINS" to be as follows:-
The skins and hides are operated upon in the following manner :-If the
skins are dry, I first soak them in a lukewarm solution of chloride of sodium,
of hydro-sulphuret of soda, of bicarbonate of soda, or carbonate of lime, but
when the skins are fresh they do not require this preparation, but are placed
at once upon the horse.
The horse is a smooth surface upon which the skins are shaved with a tool
somewhat resembling a plane. This tool consists of a piece of wood in which
a blade of steel slides in a groove, and is fixed there by two screws which pass
through the top part of the plane. There is a roller of copper in front of the
plane which keeps the plane at the proper level; this roller is kept in position
by supports placed at the side of the plane; on each side of this tool two small
plates act as guides. After being shaved, the skins are coated with a compo-
sition composed of hydro-sulphuret of soda, hydrate of lime, pipeclay, and water;
at the end of an hour they clean with facility, and are cleaned upon the horse,
washed, and the flesh removed; they are then placed into a bath of warm water

page_text: containing phosphoric acid or phosphorous acid and nitric acid. It is in this
bath they are softened. After being taken out they are squeezed, washed, and
are ready for tanning. The phosphoric acid is only useful for skins of calves,
goats, sheep, &c.; for skins of oxen, cows, or other large skins it is replaced by
a bath of sur-pyroliguite of lead in which the skins swell; after this operation
they imbibe the tanning principles more easily.
The skins prepared with the sur-pyrolignite of lead should be subjected to
numerous washings before being tanned. The washings are performed in
pits or tubs with slightly inclined bottoms over which are false bottoms covered
with metal cloth; there are also draining wells and exhaust pumps. The skins
are placed in the pits as usual, but the bark employed in the pits is replaced by
ligneous matters, such as sawdust, chips of wood, spent tan, which I purify
by boiling them four times, twice with boiling water, once with water
containing bicarbonate of soda, and once with water containing sulphuric or
hydrochloric acid. These pits are filled with clarified tanning extracts obtained
by an apparatus consisting of a tub of wood or metal communicating from the
bottom by a tube and cock with a steam boiler, and a second pipe and tap,
also placed in the bottom of the apparatus, communicating with a reservoir of
water. This apparatus contains a false bottom, a lid loaded with weights, and
several metallic cloths; the tanning matters are placed between the false bottom
and the lid; a metal tube surmounted with a rose pierced with holes is fixed in
the middle of the false bottom. The steam pipe already mentioned is bent so
as to be vertically under the tube to which the rose is attached; the water
enclosed between the bottom and the false bottom is boiled by steam coming
from this pipe, and it is thrown into the opening of the tube with the rose, and
it is showered in fine rain upon the top of the bark, and filters through the
whole of the bed and returns into the bottom of the tub, when it is again pro-
jected by the force of the steam into the interior of the tub; this operation
lasts until the water is converted after several washings over the barks into a
concentrated extract. These extracts are drawn out of the tub or apparatus
by the aid of cocks; they are received into reservoirs, and used when they
are completely cooled. The apparatus is provided with an indicator, which
indicates the level of the water necessary for the washing of the tanning
matters enclosed in the apparatus.