380 M. C. Lea—Ammonia-argentic Iodide. 
from violet-black to dark-brown), and may then be exposed 
to light either under liquid ammonia or under pure water, in 
either case the bleaching takes place, though in the latter case 
more slowly. 
If the experiment be performed in a test-tube, the bleaching 
under ammonia requires several hours, under water from one 
to three days. But if the iodide be formed upon paper, and 
this paper be exposed to light, washing it constantly with 
liquid ammonia, the darkening followed by the bleaching 
requires little more than a minute. In this case, however, the 
depend hee the escape of ammonia, for if the darkened am- 
monia iodide 
washed with water, and this water gave distinct indications of 
iodine. The iodine present is in so small quantity that it may 
easily be overlooked, but it is certainly there. The washing 
given to the AgI was so thorough that it seemed impossible to 
admit that traces of KI remained attached to the AgI, but in 
When Ag! is blackened under ammonia in a test-tube, and 
the uncorked test-tube is set aside in the dark for a day or two, 
the AgI assumes a singular pinkish shade. It thus appears 
that AgI under the influence of ammonia and of light gives 
indications of most of the colors of the spectrum. Startin, 
ays, seem to give hope of 
te method of heliochromy- 
