) 
Photographic Notes. 10g 
The New ‘‘Flash”’ Light.—Our photographic friends will do 
well to remember that all flash-powders containing chlorate are 
undoubtedly very dangerous. 
A New Transparent and Flexible Support.—M. Froedman 
has just discovered a new process for rendering gelatine, glue, and 
other bodies of the same class insoluble, by treating them with the 
salts of chromium, as bichromate of potash. This process also 
consists in transforming these bodies into colourless, transparent, 
and flexible membranes, by the use of sulphuric acid and its 
compounds. In this manner a flexible support may be obtained 
which can take the place of glass in the various photographic 
processes. For the photographic operations proceed as follows :— 
Take gelatine of good quality, soak it in water, and dissolve; then 
add bichromate of potash, and finally some alcohol, in order that 
the gelatine may flow more easily over polished plates. If need 
be, add a little glycerine to give the required degree of flexibility 
and softness. 
Before spreading the bichromatised gelatine over the plate, the 
‘plate should be coated with Mendon chalk, then on this surface is 
floated collodion (enamelled), containing the necessary quantity of 
castor oil. As soon as the collodion sets, plunge the plate into 
water until the surface no longer presents an adipose appearance, 
and then from the warm solution of chrome salt into gelatine, and 
dry in a warm room. Instead of placing the collodion on the 
polished plate, a border may be made with caoutchouc, dissolved 
in benzole, to keep the membrane in place during treatment. 
This being done, expose the plates to sunlight or in the shade, 
to convert the matter into an insoluble compound. Place another 
border around the plate, wash to remove the unchanged chrome 
salt, plunge into a solution of sulphuric acid, and then wash. 
This membrane is adapted to receiving a photographic emulsion. 
Here are the proportions recommended by the inventor :— 
Gelatine ae Srele ns ae Dats. 
Wi@tEE” Shen nei ay 6. 
Bichromate of Potash oe ae ee 
Glycerine Sea en Oe! 5, 
Alcohol) 3: one ee RAN 3 
This new and transparent flexible substance may be used for 
all manufactures in which similar matters enter; it can also serve 
as a basis for photographic prints, to be used in making transpa- 
rent signs.—/ournal de Industrie Photographique. 
Wor. 0. 6—6 
