IMPROVEMENTS IN THE MANUFACTURE OF HARD INDIA-RUBBER AND OF ARTICLES COMPOSED OF THAT MATERIAL
Year: 1855

page_text: application for Letters atent was not given numin the time prescribed
by the Act.)
PROVISIONAL SPECIFICATION left by John Henry Johnson at the Office
of the Commissioners of Patents, with his Petition, on the 7th March
1855. A communication.
I, JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of
Middlesex, and of Glasgow, North Britain, Gentleman, do hereby declare the
nature of the said Invention for "IMPROVEMENTS IN THE MANUFACTURE OF HARD
INDIA-RUBBER AND OF ARTICLES COMPOSED OF THAT MATERIAL," a communication
from Charles Morey, of Paris, in the Empire of France, Esquire, to be as
follows:-
This Invention relates to an improved system or mode of producing hard
india-rubber and articles composed thereof whereby such articles may be
produced at a less expence & with greater facility than has hitherto been
effected. The improvements consist in hardening the soft india-rubber or articles
composed of soft india-rubber by immersing them in a bath of melted sulphur
contained in an open vessel, in place of submitting them to the action of
sulphur in a closed vessel under steam pressure, which greatly impedes the
effectual carrying out of the process, since the material or articles under
treatment cannot be inspected by the workman, for the purpose of ascertaining
the progress of the vulcanization, and involves the necessity also of employing
moulds (when moulded articles are to be produced) of sufficient strength to
withstand the pressure in the vulcanizing vessel.

page_text: This sulphur bath answers the twofold purpose of supplying the necessary
sulphur for hardening and giving the requisite amount of heat for that purpose.
In manufacturing sheets or articles of hard india-rubber by this process, the
purified caoutchouc is first reduced, as in the method at present adopted, to
sheets, or to objects of various forms, by softening and triturating it. It is then
rolled out, or submitted while in the form of blocks to leavy pressure. In this
state the soft caoutchouc may be moulded into any desired form, and may be
fixed to articles or bodies of an entirely different nature, and will adhere firmly
thereto.
The objects to be hardened having received the desired form, are now
plunged into a bath of melted sulphur, which is kept at a temperature varying
from 100° to 150° centigrade. In order that the articles which are in a soft or
plastic state may not lose their form, they are suspended by wires or plates in
the sulphur, or they may be contained in suitable moulds, care being taken to
leave as many points, in contact with the sulphur as possible. These moulds
may be composed of fusible metal, similar to type metal, or the moulds may be
composed of sulphur, so that the material contained therein, on being submitted
to the action of heat, will become perfectly and rapidly vulcanized. The
hardness of the material will increase with the time of immersion in the bath,
which may vary from two hours to several days, according to the thickness of
the substance and amount of surface in actual contact with the sulphur. When
the articles are sufficiently hard they are removed from the bath, and any
sulphur adhering to them is removed, when they may be polished at once. By
incorporating a certain amount of powdered sulphur with the material before
immersing, the length of time requisite for it to remain in the bath will be
greatly reduced. Should the color or elasticity of the articles require modifying,
a little shell lac, lamp black, oxide, or other substances may be incorporated
with the soft caoutchouc during its preparation. By this process a great saving
in moulds is effected, as they are merely required to give the requisite form to
the article while the caoutchouc is in a soft state, and consequently moulds of
a slighter description may be used, and may be preserved and re-employed,
since the articles are removed therefrom when placed in the sulphur bath.