This mixture is kept hot for half an hour and then filtered, the precipitate which remains on the filter is now washed in several waters, and finally again dissolved in a solution of
| Alcohol | 250 ccm. |
| Chinin sulphate | 0.8 g. |
The latter is first dissolved in a little alcohol by heating, then the volume is added to until the amount is reached. The filtered fluid has a beautiful greenish-blue color. This forms the stock solution.
To sensitize the plates, make the following bath, pour in graduate:
| Indophenal solution (as above) | 4 ccm. |
| Malachite green (stock solution) | 4 ccm. |
| Water (distilled) | 600 ccm. |
Pour 60 ccm. of this solution in a tray (13 by 18 cm.) cover the plates and soak 2 minutes, keeping the tray in constant motion. During the operation all red rays must be carefully excluded; then the plate is drained and dried in absolute darkness.
Plates so treated are much quicker than when in their normal condition. They give the reds in their true color value, even through an intensive yellow color screen. Even this extreme color sensibility can be enhanced with the use of a “supplementary-ray filter” (“Ergänzungs-Strahlen filter”), which is made from a substance which absorbs all colors except the reds and yellow. Gelatine, dyed by soaking in a erythrosin solution, furnishes an excellent Ergänzungs-Strahlen filter, which is used in connection with the usual yellow color screen
M. Leon Vidal.
PHOTOGRAPHY IN ROME.
The Bollettino, a journal published every two months in Rome, and the chief organ of those interested in photography in that city, gives the result of the last election of members of its Photographic Society as follows: Adler, Dottor Vittoria; Intriglio, Avv. Benedetto; Tenerani, Cav. Carlo; and of the correspondent members--Calvaria, Cav. Avv. Giuseppe, of Castellamare di Stabia; Daniele, Oreste, of Catania; Garzia, Oronzo, of Maglie; Hermans, Charles, of Brussels; and Orsini, Marchese Antonio, of Solmona.