TANNING LEATHER BY ELECTRICITY
Year: 1883

page_text: LETTERS PATENT to Lucien Gaulard of Langham Street in the County of
Middlesex, for an Invention of "TANNING LEATHER BY ELECTRICITY
COMPLETE SPECIFICATION filed by the said Lucien Gaulard at the Office
of the Commissioners of Patents on the 20th February 1883.
LUCIEN GAULARD of Langham Street in the County of Middlesex "TANNING
LEATHER BY ELECTRICITY,"
In a patent obtained on the 19th September 1877, I claimed the application of
the decomposition of water by means of electricity to the tanning of leather, and
described a special arrangement of the vessel and electrodes whereby I was enabled
to effect this result.
Practical experience with this process however has proved to me that the
following arrangements are more efficient :-
Instead of placing both of the poles in the middle of the vessel, and thus causing
the two gases evolved by the decomposition of the water to act simultaneously one
only of the electrodes is placed in the centre of the vessel, the other being arranged
in a parallel plane, but in a corner, and in the centre of a passage or conduit
arranged as illustrated in the accompanying drawing, that is to say extending to
about four inches from the bottom of the vessel.-The vessel is filled with weak
liquor, and the hides are suspended therein from wooden cross bars resting on the
sides of the said vessel-The electric current is then caused to pass in such a
manner that the negative pole is in the centre of the vessel, and the positive pole is
in the conduit. Under these conditions, the hydrogen alone acts upon the leather,
and causes the rapid destruction of the nitrogenous matter contained therein.-
After undergoing this treatment for a period of eight days, the liquid in the vessel
is removed and replaced by a stronger solution of tannin, marking about twenty
degrees. The current is then reversed, so that the pole in the middle of the vessel.
becomes the positive pole, and the pole in the conduit becomes the negative pole
The oxygen alone then acts upon the liquid, thereby inducing a rapid oxidization
of the tannin, and its precipitation in this condition in the cells formed by the

page_text: gelatine, and fibrine of the hide.-The hydrogen resulting from the decomposition
of the water escapes into the atmosphere through the conduit-Under these
conditions, the tanning is effected in about fifteen days, and in order to make the
leather more weighty, it will suffice to strengthen the liquid or to place the hides
in alternate layers of tannin and leather as in the ordinary method, at the same
time keeping up the electrical action.-A wooden grating arranged at a height of
about eight inches from the bottom of the vessel is employed to keep the electrode
from direct contact with the leather, as shown in the drawing.
Having now particularly described and ascertained the nature of the said
Invention and in what manner the same is to be performed, I hereby declare that
I claim in regard to this Invention not only the novel arrangements herein before
described, but I likewise claim the substitution for simultaneous action of two
gases, the alternate action first of the one and then of the other gas, substantially
as above set forth and described.
In Witness whereof I the said Lucien Gaulard have hereunto set my hand and
seal this Eighth day of February in the year of our Lord one thousand eight
hundred and eighty three