IMPROVEMENTS IN TANNING, AND IN THE APPARATUS EMPLOYED THEREIN
Year: 1861

page_text: PROVISIONAL SPECIFICATION left by Augustin François Ménard at the
Office of the Commissioners of Patents, with his Petition, on the 14th
March 1861. A communication from Yves Auguste Rehn, residing
at Basseyutz, Department of the Moselle, Empire of France, Sugar
Baker.
I, AUGUSTIN FRANÇOIS MENARD, of No. 10, Rue de Strasbourg, in the City
of Paris, in the Empire of France, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN TANNING, AND IN THE APPARATUS EMPLOYED
THEREIN," (a communication,) to be as follows:-
This Invention relates to a new and rapid system of tanning leather of
every kind, and consists, first, in the use of bark in bundles instead of being
reduced to powder, as in the ordinary method.
Secondly, the peculiar arrangement of the apparatus to be employed.
Thirdly, the employment of carbonic acid and other gas, whether the
tanning is performed in a vacuum by hydrostatic pressure, or by the old
method.
Fourthly, the mode of operating upon the skins in the vats by the injection
of various gases combined with electric and galvanic currents, to effect the
rapid tanning of the leather.
Fifthly, placing the skins in calcareous, magnesian, aluminous, silicious, or
ferruginous solutions, in which is injected various gases in combination with
an electric and galvanic current for the formation of substances required
in tanning.

page_text: Sixthly, in the mode described for constantly preserving the strength of
the tannin solution at any temperature or condition of the atmosphere, and
preventing the formation of gallic acid by means of carbonic acid.
Seventhly, the application of carbonic acid and other compounds of carbon
to form chemical compounds with the mineral substances herein-after
described.
Eighthly, in rendering leather more pliable and more impermeable to water
by the saponification of fatty matters with sulphurets of carbon.
In carrying out my Invention I form solutions of tannin of different degrees
of strength with bundles of oak bark. These solutions are placed in a series
of vats, vessels, or pits arranged in parallel lines, or in any other convenient
manner. The skins are plunged in the said vats or vessels, and operated upon
alternately by contact with the tanning liquids in combination with solutions
of aluminum, calcium, sodium, and other similar bodies, in which is injected
carbonic acid gas, or compounds of carbon, gaseous or liquid, according to the
quality and use of the leather required, for the purpose of gradually coagulating
the gelatine and albumen of the skins. By the action of electricity, and
forcing currents of gas into the solutions, the pores of the skins become
opened, and the tanning of the leather is rapidly effected. Other barks may
be employed instead of oak bark to form solutions of tannin, and producing
tannate of gelatine under the action of carbonic acid.
For steeping and taking the hair off the skins I adopt the following
method:-I expose the skins to the action of currents or jets of steam and
gas in a suitable vessel, which are simultaneously brought into contact with
them, and which cause the skins to be freed from hair in more or less time
according to the nature and quality of the leather required. I dispense with
the ordinary process of passing the skins through acidulated liquor vats, and
proceed at once with the tanning after the operation of washing.
DESCRIPTION OF THE MODE OF TANNING.
I employ vats or vessels furnished with pipes, by which a communication is
formed one with the other, thus allowing the overflow of the tanning liquids
from one vat to another in a gradually diluted and weakened state.. These
vats or pits are fed by a continuous stream of tanning solutions supplied from
suitable reservoirs of extracting and macerating apparatus, in which the bark
is placed and operated upon, and as the solutions flow from one vat to another
they permeate the skins and carry off the gases taken up by them. The vats
or pits to the number of forty (for example) are arranged in two series
parallel to each other, or in a circle, or other convenient manner. The

page_text: solution of tannin flows one into the other from vat No. 1 to No. 40. The
bundles of bark (or any other substance containing tannin) are put two or
three times each day into vat No. 20, whence they are taken to vat No. 19,
then to No. 18, and so on until they arrive at No. 1, after which fresh bark
is placed in No. 20, and an equal quantity of spent bark withdrawn from
No. 1, the bark having remained the same length of time in each vat or
vessel. The solution of tannin having acquired its greatest density in vat
No. 20 then decreases in strength until it reaches vat No. 40, whence it flows
into a reservoir, from which it is conveyed to the vats to be again strengthened
with bark. The vats No. 20 to 40 inclusive, are furnished with a false
bottom pierced with holes. Between these bottoms a pipe is introduced to
convey carbonic acid gas into the vats for the purpose of preventing decom-
position of the tannin solutions therein, and the formation of gallic acid. I
establish by any suitable and convenient means an electric or galvanic current
in four vats (of the series No. 20 to 40) containing solutions of lime,
phosphate of lime, barytes, alumina, or magnesia in combination with gases to
assist the action of the tannin on the skins. The different mineral substances
may be rendered acid by an admixture of hydrochloric or nitric acid, and
rendered alkaline by ammonia or potash. I make leather impervious to water
by fixing therein grease and resin dissolved in sulphuret of carbon.