with the material of the latent Photographie Image. 481 
black which by treatment with HCl became a little lighter. 
When this product was washed and boiled with strong nitric 
acid, it acquired a fine deep copper red color, the acid taking 
up silver. This red substance dissolved in ammonia readily, 
leaving a small amount of black residue; the same with sodium 
hyposulphite. ) 
(This examination, madea year ago, has recently been repeated 
with a view to obtaining a quantitative determination of the 
proportion of Ag,Cl contained in the red product. The expo- 
sure was for about a day, the oxalate at the end of the exposure 
seemed absolutely black. After treatment with HCl it assumed 
a purple black shade. After thorough washing and boiling 
with dilute nitric acid, which removed a large quantity of sil- 
ver, perhaps 12 or 15 per cent of the entire quantity, it had 
a fine lilac purple color. Analysis showed that it contained 
about one-half of one per cent of subchloride, or more exactly, 
0:45 per cent Ag,Cl was found). 
The red chloride thus obtained from silver oxalate, not only 
closely resembles the red chloride obtained by means exclu- 
sively chemical, but shows the same behavior to reagents. 
Treated with ammonia it dissolves leaving a black residue. 
The formation of this residue takes place precisely in the same 
manner with both substances. As fast as the material dissolves 
the liquid becomes clouded and an extremely fine black sub- 
stance seems to form within it, which gradually falls to the 
bottom. 
Treated with solutions of the alkaline haloids, the red chlo- 
ride derived from exposed silver oxalate remains unchanged 
after 24 hours contact with potassic chloride and becomes paler 
and more lilac under potassic bromide; under potassic iodide 
becomes gray. These reactions correspond with those of the 
photochloride. 
Silver phosphate belongs to the more sensitive silver salts and 
easily darkens in sunlight. Ina few hours it becomes greenish 
all through, after which further exposure produces little visible 
effect. This product becomes with HCl quickly gray, and by 
treatment with nitric acid after washing, light pink. 
Silver tartrate by exposure to sun became quite black. With 
HCl this changed to reddish gray or dull pink. This product 
well washed and let stand with cold nitric acid 1°36 became 
first lavender and then light pink. 
Silver carbonate by prolonged exposure became greenish 
black, and with the above treatment yielded a dull pink 
photochloride. 
Silver pyrophosphate even by several days’ exposure to win- 
ter sun did not blacken, but assumed an ochreous or buff shade. 
With HCl this passed to a sort of salmon pink and by heating 
Am. Jour. Sci.—Tuirp Series, Vout. XXXII, No. 198.—JuNeE, 1887. 
30 
