Year: 1894

page_text: Date of Application, 31st Oct., 1894-Accepted, 1st Dec., 1894
These ingredients I thoroughly dissolve in water, and then add to the solution so
formed, one half-teaspoonful of chrome alum previously dissolved.
The above salting solution, is applied to the plain paper in the form of a bath, or
in any other suitable manner.
The next stage consists in treating the paper with the silvering solution, which
is composed of the following ingredients in or about the hereinafter stated
proportions.
I take of nitrate of silver, one half-pound and dissolve same in distilled water
until by suitably testing, the solution is found to be seventy per cent. in strength.
I do not add all the water at first to the nitrate of silver to reduce same to the
above mentioned strength, but merely add to the said nitrate of silver sufficient
water to cover same and then put into the vessel holding same, iodide of potash in
suitable proportion.
To this composition I now add one ounce of acetic acid and one drachm of
nitric acid.
The paper is treated with the above solution in any suitable manner, and during
such treatment should black spots appear upon the surface of such print, I add a
few more drops of nitric acid.
For cleaning and brightening the work, I employ a strong solution of hydro-
sulphite of soda.
The stage following the above, consists in treating the print with a solution to
develop the outlines of the subject, and the solution I employ is made up of the
following ingredients in or about the hereinafter mentioned proportions:
I take of ordinary glue, two pounds; and place this in a vessel containing two
gallons of water, which I boil until by evaporation same is reduced to about half a
gallon, which is then allowed to cool until it is milk or luke-warm.
To this solution is added one quarter of a pound of granulated zinc which has
been covered with sulphuric acid and allowed to stand for one hour, the whole
mixture then being heated in a suitable vessel for four hours, care being taken to
carefully stir the mixture while it boils, which it is allowed to do until it is of the
Din Q77

page_text: consistency of syrup. To this mixture is now added ten pounds of sulphate of
iron dissolved in ten gallons of water, the whole solution being then tested by the
use of a hydrometer to ascertain the strength of such solution, which should be
forty per cent. in strength.
There is now added to the solution so formed, two pounds of solution of acetic
acid No. 8, the whole being well stirred, after which two ounces of nitric acid, or a
sufficient quantity of the latter to render the print visible, is added.
If the said print develops too rapidly or is mottled, more acetic acid may be
added, or if the print is not black enough I may add more sulphate of iron.
To clean the nearly finished print, I take of crystallized iodine a sufficient
quantity and add thereto a sufficient quantity of iodine of potash, the whole of
which place in a suitable vessel and cover with water, care being taken to
thoroughly shake the mixture, after which it is diluted until it is of the colour of
sherry wine, and then cleared and brightened by a strong solution of cyanide of
potassium.
If the whole solution so prepared, is hyper-yellow, more cyanide of potassium
may be added thereto.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. In the process of printing from a photographic negative upon paper, the
employment of a salting solution, composed of the ingredients and in or about the
proportions, substantially as specified.
2. In the process of printing from a photographic negative upon paper, the
employment of a silver solution, composed of the ingredients and in about the
proportions, substantially as hereinbefore described.
3. The developing solution (for use in the process of printing from a negative
upon paper having a surface unprepared with gelatine), made up of the ingredients
mixed together in or about the proportions substantially as specified.
4. The employment of, in the process of printing upon paper from a photographic
negative, a solution for cleaning the print, composed of the various ingredients used
in or about the proportions substantially as described.
Dated this 31st day of October 1894.
HUGHES, SON & Co.,
38, Chancery Lane, London, Agents for the Applicant.