IMPROVEMENTS IN AND RELATING TO MEANS FOR PRODUCING MULTIPLE COPIES OF WRITING, DRAWINGS, AND THE LIKE
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by William Robert Lake at the Office
of the Commissioners of Patents on the 5th July 1881. A communication
from abroad by Heinrich Schnitt, of Prague, Austria.
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London. "IMPROVEMENTS IN AND RELATING TO MEANS
FOR PRODUCING MULTIPLE COPIES OF WRITING, DRAWINGS, AND THE LIKE."
[A communication from abroad by Heinrich Schmitt, of Prague, Austria.]
The present improvements relate, first, to compositions, masses, or beds, containing
gelatine, which serve as printing surfaces after a sheet of paper (upon which
whatever has to be reproduced has been written, drawn, or printed, by a specially
prepared ink) has been laid face downwards on the said composition or bed and
afterwards drawn off so as to leave a reverse copy on the composition. The afore-
said gelatinous compositions as well as the ink with which the writing or drawings
to be multiplied are executed may be made of different materials according to
whether the composition is intended to serve as means for obtaining copies in oily
printing ink or whether it is to yield copies in aniline colors.
To distinguish these two kinds of compositions or masses, I will call the first
kind X and the second kind Y. The composition Y may be of any of the known
kinds.
To make the composition or mass X I pour into a shallow pan a warm solution,
consisting of 16 parts water, one part glycerine, and one thousandth part chrome
alum. When this composition has become cold and hard it can be used for
printing purposes, after being made damp. The writing or drawing to be
multiplied by means of the mass or bed X is made on paper with an ink
containing a salt of uranium, and preferably composed of about one part of
nitrate of uranium, 5 parts water, and one part coloring matter, for instance,
indigo. When the paper has been laid with its written surface on this bed X and
drawn off again it will leave traces of the ink on the bed, which will exert a
chemical action thereon, enabling the parts touched by it to receive printing ink,
whilst the other parts will repel the printing ink. The process of printing on the
bed X can then take place in the usual way by applying the printing ink with a
roller, and then passing on the sheet of paper which is to receive the impression.

page_text: Instead of casting the aforesaid composition of the bed X in a pan, or providing
the composition with a backing of paper or zinc or other material, I can make
it into sheets or leaves of about one thirtieth of an inch in thickness without
any backing. When a sheet of this kind is to be used for printing purposes
it is damped on its back, and will then be adhesive enough to enable it to be
attached to a smooth surface.
The said improvements refer, secondly, to the use of a salt of uranium for the
composition of a printing ink, the impressions of which on paper will when drawn
off on the gelatinous bed X act upon the bed in the same manner as the aforesaid
writing ink containing a uranium salt. This printing ink may be suitably made
by rubbing up one part of glycerine of 30 degrees Baumé with one part of nitrate
of uranium, and then rubbing up this mixture with eight parts of ordinary
printing ink.
The said improvements refer, thirdly, to means for removing the traces of either
of the two kinds of ink from the aforesaid beds X or Y so as to make them fit for
repeated use.
The action of the uranium salt on a bed or mass of the kind indicated by the
letter X can be removed by the use of a solvent of the said salt, for instance, an
acid like diluted nitric acid or acetic acid, or by a powerful base, like caustic soda,
or by a salt, like carbonate of ammonia or bicarbonate of soda. It is preferable to
use bicarbonate of soda as it has no disagreeable odor and does not spoil the
gelatine. A solution of one part of bicarbonate of seda in 12 parts of water
brushed over the gelatine for one or two minutes dissolves the uranium salt and is
then washed off. The remaining traces of bicarbonate of soda can be removed
with water or by the aid of a little vinegar. The bed or mass can then be used
again for printing purposes.
From a bed of the kind indicated by the letter Y the aniline ink may be
removed without removing the surface of the gelatinous bed by using a precipitant
of the aniline colors, i.e., of the methyl violet ink, or of the fuchsine anilin-acetate
ink. Such a precipitant is formed by dissolving one gramme of tannin in one
hundred parts of water and adding about 20 drops of nitric acid. The nitric acid
is added for the purpose of preventing the indurating action of the tannin on the
gelatine of the bed or mass. The surface of the bed after being washed with this
solution is ready for use again.
To enable a person to write or draw on paper with a concentrated solution of
an aniline color I provide paper coated with ordinary gum.