Photography. 123 
PHoToGRAPHY.— 
11. Dry Process ; by MM. TrtsskrE et Jacquremet, of Marseilles — 
Any eollodion which gives good results by the wet process may be used 
in this, provided that it contains at least one per cent of iodids and 4 per 
cent of bromids. The following formula is recommended : 
Ether, - - - - - - - - 60 cub. c. m.* 
Alcohol, - - - - - - - 40 - 
Gun cott - - - - - - gram. 
Todid of ‘cadmium, - - - - - O70 uc 5° 
monium, - . - . bats ag 
Bromid ork ammonium, - 0-40 “ 
The plate is covered as usual, ina sesitewea® ina bath containing 
Distilled water, - - - - - . be cub. $:: m. 
Nitrate of silver, -- - - - - 8 gra 
Glacial acetic acid, - - eee ae y m. 
The plate is then snarl toa bath of distilled and filtered water, 
where it should remain until the plate ceases to appear oily. It is aa 
passed successively through three other baths of filtered water. 
first two, filtered spring water may be used, but the last should be “illed 
with distilled water. 
The plate is next washed in a solution of tannin, containing 
Distilled water, - - 100 cub. ¢. m. 
Tannin, - - - . - - 3 grams. 
Alcohol of 40 pr. ct. -  5Scub.¢c.m. 
In preparing this solution the tannin ito : first dissolved in the 
pure water, and filtered before the alcohol is a efore applying 
placed in rede See That from the first glass should be — 
treatment of a seco ate. -Lastly, the plate is washed under a ta 
supplied with pure water to remove the excess of tannin, and air dried. 
1 f exposure for views is stated as from 1 to 14 minutes with 
a quarter plate Jamin view-lens of 10 c. m. focus, under best conditions. 
fine camel’s hai Having soaked the plate for a few minutes in 
pure water, it is next di in the silver bath used for sensitizing and 
drained. It is then dipped into ‘a shallow flat glass dish containing a 
sufficient quantity of the gee ersinn y 
oso water, - - - a bi “i m. 
yrogal lie acid, - w es * a a 
Glacial acetic acid, - - - - 10 cub. cm. 
By rocking the dish the liquid i is kept = pene over the sur- 
te and the dev re eee is carefully watched by the | ight transmitted 
t a the glass 
@ exposu e has been well timed the image will appear slowly, but 
aa all the dacs sharply defined and the lights wholly unstained. It 
is then only necessary to add to the ore a few drops ata time, of 
a weak solution of nitrate silver until the blacks are sufficiently intense 
* 98-84 cubic centimeters = 1 liquid ounce, 1 gram = 15-4 grains, 
