AN IMPROVED METHOD OF CURING INDIA-RUBBER OR GUTTA PERCHA COMPOUNDS
Year: 1859

page_text: LETTERS PATENT to John Talbot Pitman, of the American and European
Patent Offices, No. 67, Gracechurch Street, London, for the Invention
of "AN IMPROVED METHOD OF CURING INDIA-RUBBER OR GUTTA PERCHA
COMPOUNDS." A communication from abroad by Asahel Knowlton Eaton,
of New York, City in the State of New York, one of the United States
of America
Sealed the 15th May 1860, and dated the 21st November 1859.
PROVISIONAL SPECIFICATION left by the said John Talbot Pitman
at the Office of the Commissioners of Patents, with his Petition, on
the 21st November 1859.
I, JOHN TALBOT PITMAN, of the American and European Patent Offices,
No. 67, Gracechurch Street, London, do hereby declare the nature of the.
said Invention for "AN IMPROVED METHOD OF CURING INDIA-RUBBER OR GUTTA
PERCHA COMPOUNDS," a communication to me from abroad by Asahel Knowlton
Eaton, of New York, City in the State of New York, one of the United States
of America, to be as follows:-
It consists in the use of a bath composed of metals, combination of substances
or alloys capable of fusing at or below the lowest degree of temperature, and
of being elevated by heat readily to the highest temperature required in the
process of vulcanizing (so called) substances. The alloy may consist of
bismuth, lead, and tin in required proportions, mercury in certain cases may
be used. I do not, however, confine myself to the employment of any par-

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John Talbot Pitman in the Great Seal Patent Office on the
16th May 1860.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
TALBOT PITMAN, of the American and European Patent Offices, No. 67,
Gracechurch Street, London, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-first day of November, in the year of our Lord
One thousand eight hundred and fifty-nine, in the
year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said John Talbot Pitman, Her special licence that I, the said John
Talbot Pitman, my executors, administrators, and assigns, or such others
as I, the said John Talbot Pitman, my executors, administrators, and
assigns, should at any time agree with, and no others, from time to time
and at all times thereafter during the term therein expressed, should and
lawfully might make, use, exercise, and vend, within the United Kingdom of
Great Britain and Ireland, the Channel Islands, and Isle of Man, an Invention
for "AN IMPROVED METHOD OF CURING INDIA-RUBBER OR GUTTA PERCHA COM-
POUNDS," a communication from abroad by Asabel Knowlton Eaton, of New
York, City in the State of New York, one of the United States of America,
upon the condition (amongst others) that I, the said John Talbot Pitman, my
executors or administrators, by an instrument in writing under my, or their, or
one of their hands and seals, should particularly describe and ascertain the
nature of the said Invention, and in what manner the same was to be per-
formed, and cause the same to be filed in the Great Seal Patent Office
within six calendar months next and immediately after the date of the said
Letters Patent.
NOW KNOW YE, that I, the said John Talbot Pitman, do hereby
declare the nature of the said Invention, and in what manner the same
is to be performed, to be particularly'described and ascertained in and by the
following statement :-
It consists in the use of a metallic bath, so constituted as to fuse at or below
the lowest degree of temperature required in vulcanization, and capable of
being elevated readily to the highest temperature required in the process.

page_text: Preparations of india-rubber and sulphur, or india-rubber combined with any
vulcanizing agent or agents immersed in such a bath when at its fusing point
are thoroughly vulcanized in from two to five hours, according to the
temperature maintained. Preparations of gutta percha are similarly affected,
and the process is equally adapted to the manufacture of soft and hard gutta
percha or india-rubber. The composition of the bath may be varied to meet
any required case, but as it is more convenient to use one of a low fusing
point it will perhaps be well, usually to make use of an alloy 50 parts of
bismuth, 31 of lead, and 19 of tin, fusing at about 203 degrees Fahrenheit.
When the articles to be vulcanized will bear a higher temperature than 212
degrees in the early stages of the process a bath of higher fusing point may
be used, and the above alloy may be modified accordingly, it may be made
less fusible by increasing the proportion of tin and lead, and by the addition of
zinc or other metal. Mercury alone might be used as a bath but would be
expensive, and when used in an open vessel objectionable on account of the
mercurial vapors that would be evolved. It may be used in small proportions
however, for the purpose of increasing the fusibility of alloys. The process
can be conducted in any open iron vessel, and the temperature regulated by
means of a thermometer inserted in the bath. The articles may, if desired,
be transferred from one bath to another successively in order to avoid the
necessity of materially raising the temperature of a single bath. For instance
articles may be immersed in a bath ranging from 212 degrees to 220 degrees
for one hour for the purpose of expelling moisture and commencing the
process of vulcanization, and then transferred to another bath varying from
225 degrees to 230 degrees, and so continue until the highest desirable point
of temperature has been reached. In the vulcanization of fine soft goods I
prefer to raise the temperature of the bath only 225 degrees during the first hour
and gradually elevate to 275 degrees in five hours from the time of the first
immersion. If the articles to be vulcanized are of a coarser quality they may
be vulcanized in two hours by bringing up the temperature during that time to
300 degrees.
The value of this Invention consists in the following points of superiority
over the ordinary mode of treating india-rubber or gutta percha.
1st, the great convenience arising from the air of an open apparatus, into
which articles may be immersed, or from which they may be withdrawn at any
time during the heat.
2nd, the absolute certainty with regard to the time when the articles are
completely vulcanized, trial samples being withdrawn from time to time to
determine the state of the goods.

page_text: 3rd, the perfect exclusion of air and moisture, which exclusion is essential
to the more satisfactory results.
4th, much greater uniformity of temperature, every article and every part of
each article being equally affected.
Having now described the Invention, and the manner in which it is to be 5
operated, as communicated to me, what I claim and desire to secure under
the herein-before in part recited Letters Patent, is the use of a metallic bath
substantially as herein described for the purposes of vulcanization.
In witness whereof, I, the said John Talbot Pitman, have hereunto set
my hand and seal, on this First day of May, Anno Domini One 1
thousand eight hundred and sixty.
JOHN T. PITMAN. (L.S.)