IMPROVEMENTS IN THE PREPARATION OF GLASS FOR SILVERING AND IN COMPOUNDS THEREFOR.”
Year: 1876

page_text: LETTERS PATENT to James Edmondson Pratt, of Clifton Lodge, Flodden Road,
"
Camberwell, in the County of Surrey, Glass Silverer, for the Invention of
IMPROVEMENTS IN THE PREPARATION OF GLASS FOR SILVERING AND IN
COMPOUNDS THEREFOR.”
Scaled the 23rd May 1876, and dated the 24th March 1876.
PROVISIONAL SPECIFICATION left by the said James Edmondson Pratt at
the Office of the Commissioners of Patents on the 24th March 1876.
JAMES EDMONDSON PRATT, of Clifton Lodge, Flodden Road, Camberwell, in the
County of Surrey, Glass Silverer. "IMPROVEMENTS IN THE PREPARATION OF GLASS
FOR SILVERING AND IN COMPOUNDS THEREFOR."
My Invention relates to the process of silvering glass by the use of nitrate of
silver solution, and consists in treating the glass with certain compounds or
solutions before applying the nitrate of silver solution, whereby the glass when
silvered is rendered of far greater whiteness and brilliancy than is obtainable by the
processes heretofore employed, and is quite free of the cloudiness that now frequently
occurs. For this purpose the glass having been thoroughly cleansed in the usual
manner, I first wash it over with a solution composed of one part by weight of
protochloride of tin with one hundred parts by weight of distilled water, or for
larger plates I employ a solution composed of 1 oz. of protochloride of tin with
5 drachms of oxalate of ammonia, and lb. of putty powder to 4 pints of distilled
water. This solution is applied to the plate by means of a soft rubber and allowed
to dry.
After applying either of the above solutions I wash the plate over with a solution
composed of two parts by weight of oxalate of ammonia, four parts of grape sugar,
one part of lime, and one part of cyanide of potassium dissolved in one thousand
parts of distilled water. This solution requires to be filtered before being used.
After the glass has been treated with the two solutions as above described,
it is ready for the usual silver solution of tartaric acid, ammonia, and nitrate of
silver.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said James Edmondson Pratt in the Great Seal Patent Office on the 16th
September 1876.
JAMES EDMONDSON PRATT, of Clifton Lodge, Flodden Road, Camberwell, in the
County of Surrey, Glass Silverer. "IMPROVEMENTS IN THE PREPARATION OF GLASS
FOR SILVERING AND IN COMPOUNDS THEREFOR."
My Invention relates to the process of silvering glass by the use of nitrate of
silver solution, and consists in treating the glass with certain compounds or
solutions before applying the nitrate of..silver solution, whereby the glass when
silvered is rendered of far greater whiteness and brilliancy than is obtainable by
the processes heretofore employed, and is quite free of the cloudiness that now
frequently occurs. For this purpose the glass having been thoroughly cleansed in
the usual manner, I first wash it over with a solution composed of one part by
weight of protochloride of tin with one hundred parts by weight of distilled water,
or for larger plates I employ a solution composed of 1 oz. of protochloride of tin
with 5 drachms of oxalate of ammonia, and lb. putty powder to 4 pints of distilled
water. This solution is applied to the plate by means of a soft rubber, and allowed
to dry.
After applying either of the above solutions I wash the plate over with a solution
composed of two parts by weight of oxalate of ammonia, four parts of grape sugar,
one part of lime, and one part of cyanide of potassium dissolved in one thousand
parts of distilled water. This solution requires to be filtered before being used.
After the glass has been treated with the two solutions as above described,
it is ready for the usual silver solution of tartaric acid, ammonia, and nitrate of
silver.
Although I prefer to employ the ingredients in the proportions above stated as
yielding the best results, yet I do not limit myself to these proportions as they may
be somewhat varied.
Having thus described the nature of my Invention and in what manner the same
is to be performed I claim,-
First. The process of preparing glass for silvering by first washing it with a
solution of protochloride of tin in water with or without the addition of oxalate of
ammonia and putty powder, and after this wash has dried applying a second
solution of oxalate of ammonia, grape sugar, lime, and cyanide of potassium in
water, substantially as herein described.
Second. The use for preparing glass for silvering of the compounds herein-before
described.
In witness whereof, I, the said James Edmondson Pratt, have hereunto set my
hand and seal, this Sixteenth day of September, in the year of our Lord
One thousand eight hundred and seventy-six.
J. E. PRATT. (L.S.)