An Improved Tanning Process.
Year: 1896

page_text: Date of Application, 5th Nov., 1890-
Complete Specification Left. 3rd Aug. 1897 Accented 1th Cont
4007
7600
Complete Specification Left. 3rd Aug. 1897-Accented, 4th Sept., 1907
PROVISIONAL SPECIFICATION.
An Improved Tanning Process.
I, ALEXANDER MELVILLE CLARK of the Firm of A. M. & Wm. Clark of 53,
Chancery Lane in the County of Middlesex, Fellow of the Chartered Institute of
Patent Agents; do hereby declare the nature of this Invention (a communication
to me by Les Fils de F. P. Heinrich of Schlettstadt, Alsace) to be as follows:-
This invention relates to a rapid tanning process which consists essentially in
the employment of naphthaline in the tanning liquors, particularly the weak
liquors used for the preliminary tanning of the hides, and whereby this pre-
liminary tanning is effected in such a manner that the hides can thereafter be
transferred to very strong liquors contained in a rotating vessel and be thereby
very rapidly and uniformly tanned.
It is important in this operation that the naphthaline be uniformly distributed
in the liquor.
A practical mode of carrying out the process is as follows. The hides arg
suspended for from four to six hours successively in three liquors whose respective
strengths are 1. 20, 20, and 30, Beaumé. Thereupon the hides are transferred to
a rotating drum in which they are immediately exposed to the action of a strong
liquor of about 15° Beaumé. Instead of at once submitting hides to
15° Beaumé they may be first exposed to one not so strong, say about 50 Beaumé
liquor at
and then in a second drum to the last liquor. It is in this way possible to
completely tan a thick ox-hide in about fifty hours in all.
An advantageous method of introducing the naphthaline into the liquors is to
boil five kilogrammes of naphthaline in water and then add that to about eight
cubic metres of liquor. It is most advantageous to mix the liquor from the drum
(after it has been sufficiently exhausted) with the washing water of the completely
tanned hides so as to form the third liquor of 3° Beaumé which when sufficiently
exhausted serves as a second liquor and finally as a first liquor for the preliminary
tanning.
It is best to add the naphthaline in the drum since the motion and the heat
generated favour the intimate admixture and fine distribution of the naphthaline
throughout the liquor. It is necessary always to add fresh naphthaline in which
the liquors become gradually richer.
The action of the naphthaline in the preliminary tanning is to cause the grain
as well as the entire skin to remain soft, whereas were liquors of similar strength
to be employed in the preliminary tanning without naphthaline, the grain would
become hard and brittle and shrivel up. It would appear to be due to this soft-
ess of the grain and to the uniform penetration by the tanning liquor which
the hide has experienced in the preliminary tanning, that the after-tanning in the
trong liquors can proceed of itself without any artificial assistance.
It is especially worthy of remark that the rotation of the drums can be inter-
upted without the tanning thereby suffering beyond the fact that no action of
he liquor takes place; and, further, it is worthy of note that the liquors do not

page_text: require to be kept at a constant strength but that they can diminish considerably
from their original strength.
Dated this 5th day of November 1896.
A. M. &WM. CLARK,
53, Chancery Lane, London, Chartered Patent Agents.
I, ALEXANDER MELVILLE CLARK of the Firm of A. M. & Wm. Clark of 53,
Chancery Lane in the County of Middlesex, Fellow of the Chartered Institute of
Patent Agents; do hereby declare the nature of this Invention (a communication
to me by Les Fils de F. P. Heinrich of Schlettstadt, Alsace,), and in what manner
the same is to be performed to be particularly described and ascertained in and by
the following statement :-
This invention relates to a rapid tanning process which consists essentially in
the employment of naphthaline in the tanning liquors, particularly the weak
liquors used for the preliminary tanning of the hides, and whereby this pre-
liminary tanning is effected in such a manner that the hides can thereafter be
transferred to very strong liquors contained in a rotating drum or drums and be
thereby very rapidly and uniformly tanned.
It is important that the naphthaline be uniformly distributed in the liquors
and with this object I will describe a practical mode of carrying out the process
which is as follows The hides are suspended for from four to six hour's
successively in three tanning liquors containing naphthaline and whose respective
strengths are 1.2°; 20; 3° Baumé. Thereupon the hides are transferred to a
rotating drum in which they are immediately exposed to the action of a strong
liquor of about 15° Baumé also containing naphthaline. Instead of at once sub-
mitting the hides to a liquor of 15° Baumé they may be first exposed to one not so
strong, say about 5° Baumé and then in a second drum to the last liquor. It is in
this way possible to completely tan a thick ox-hide in about fifty hours in all.
An advantageous method of introducing the naphthaline into the liquors is to
boil 5 kilos (11 lbs) of naphthaline in water and then add that to about 8 cubic
metres (17,600 gallons, of liquor. It is most advantageous to mix the liquor from
the drum (after it has been sufficiently exhausted) with the washing water used for
the completely tanned hides so as to form the third liquor of 3° Baumé which when
sufficiently exhausted serves as the second liquor and finally as the first liquor
above referred to as being used for the preliminary tanning.
It is best to add the naphthaline in the drum since the motion and the heat
generated favour the intimate admixture and fine distribution of the naphthaline
throughout the liquor. It is necessary always to add fresh naphthaline in which
the liquors become gradually richer.
The action of the naphthaline in the preliminary tanning is to cause the grain
as well as the entire skin to remain soft, whereas were liquors of similar strength
to be employed in the preliminary tanning without naphthaline, the grain would
become hard and brittle and shrivel up. It would appear to be due to this soft-
ness of the grain and to the uniform penetration by the tanning liquor which
the hide has experienced in the preliminary tanning, that the after-tanning in the
strong liquors can proceed of itself without any artificial assistance.
It is especially worthy of remark that the rotation of the drums can be inter-
rupted without the tanning thereby suffering beyond the fact that no action of
the liquor takes place; and, further, it is worthy of note that the liquors do not

page_text: require to be kept at a constant strength but that they can diminish considerably
from their original strength.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is:-
1. The herein described process of tanning leather by the employment of
naphthaline in the tanning liquors and particularly the preliminary tanning
liquors as specified.
2. The herein described method of preparing the preliminary tanning liquors
containing naphthaline which consists in adding naphthaline to the strong liquor
in the rotating drum and diluting the partially exhausted liquor with washing
water used for the tanned hides so as to obtain by the movement of the drum and
the backward progress of the liquors through the vats an even distribution of the
naphthaline in the preliminary tanning liquors.
Dated this 3rd day of August 1897.
A. M. & WM. CLARK,
53, Chancery Lane, London, Chartered Patent Agents.