IMPROVEMENTS IN MEANS AND APPARATUS FOR REPRODUCING OR COPYING LETTERS AND MANUSCRIPTS
Year: 1867

page_text: PROVISIONAL SPECIFICATION left by William Clark at the Office of the
Commissioners of Patents, with bis Petition, on the 2nd April 1867.-
A communication from abroad by Pierre Alexandre Georges Niepce de
St. Victor, Gentleman, and Manuel Leopold Jonas Lavater, India-rubber
Manufacturer, both of 29, Boulevart St. Martin, Paris.
I, WILLIAM CLARK, of 53, Chancery Lane, in the County of Middlesex,.
Engineer and Patent Agent, do hereby declare the nature of the said Inven-
tion for "IMPROVEMENTS IN MEANS AND APPARATUS FOR REPRODUCING OR COPYING
LETTERS AND MANUSCRIPTS," to be as follows:-
All inks are capable of reproduction, but those which are the most favorable
and which permit of a great number of copies being made from one original,
even after a lapse of several years, are those which are sold in trade under the
name of copying or transferring ink.
In order to obtain several copies of a letter, either newly written or old, a
sheet of tissue paper is lightly damped with a sponge, as usually done to.
obtain a copy of a letter, but in order to obtain several copies the copy on
quitting the copying press must be subjected to the vapour of liquid ammonia
(volatile alkali), which immediately causes the writing to appear, it being

page_text: often scarcely visible, and sometimes not at all. It is even a means of
causing completely invisible characters to appear on a sheet of blank paper,
and this may be done long after the copy has been made, so long as the sheet
of tissue paper is damp.
Liquid ammonia acts on all inks containing an organic matter, such as
sumac or logwood; for example, a red ink made of acidulated logwood
reproduces the impression in red, but the copy becomes black when subjected
to the vapour of ammonia, in the same manner that a black ink can become
red under the influence of an aced vapour, for example, that of hydrochloric,
azotic, or acetic acids. All alkalies in general, and especially soda, potash,
baryta, calx, and cyanide of potassium cause invisible characters to appear on
a sheet of white paper on wetting it with an alkaline solution if the original is
of transferring or copying ink.
Blue ink made of Prussian blue may be reproduced several times by
submitting the copy of the characters to the vapour of hydrochloric acid.
All colored inks containing an organic matter can be reproduced either by
an acid or an alkaline vapour, according to the composition of the ink. In order
to facilitate the reproduction, and also to increase the number of proofs,
the copying paper may be damped with water, sweetened with sugar candy,
or other sugar or viscid matter, glucose, sugar of milk, honey, or other
muciliganous, gelatinous, or resinous matter. Copying paper thus impregnated
with sugared water is ready to receive by the same process the impression of
the ordinary ink, whether freshly written or not; but by this means of com-
munication it always reproduces itself better, and extends to a greater number
of copies. In order to subject the sheet to the ammoniacal liquids, or rather
to the ammoniacal vapours, a box of suitable size may be employed in which
the sheet is enclosed, and in which ammoniacal vapours are evolved; this box
may resemble that used in the daguerreotype process for subjecting the plates
to the vapour of iodine or of bromine. It is well known that these baxes are
made in glass, porcelain, india-rubber, or bituminized cardboard, and other
similar substances, and that they are enclosed by a sliding glass in the form of
a cover, which is ground in order form an air-tight closure. Any other means
of exposure to ammoniacal vapours or of immersion in ammoniacal solutions
may be employed.
Instead of impregnating the copying paper with sugar, glucose, or other
gummy or viscid matter, the said ingredients may be incorporated in the papor
pulp in the process of manufacture. By the same means the paper may
contain in its composition matters capable of evolving at any moment required

page_text: the ammonia necessary for the reaction which renders the characters visible.
When facsimiles are required whose dimensions are too large to be received
in the apparatus indicated, the transfer is operated by placing a sheet of
impermeable paper above the copying paper, and rubbing it with a spatula
over the whole extent of the writing.