remaining after the Solution of PI atina. 417 
test of the oxide of osmium, is an infusion of galls, which pre- 
sently produces a purple colour, becoming soon after of a deep 
vivid blue. By this means, the presence of this, and of the metal 
first described, may be observed, when the two are mixed toge- 
ther. The solution of iridium is not apparently altered by being 
mixed with the oxide of osmium ; but, on adding an infusion 
of galls, the red colour of the first is instantly taken away, and 
soon after the purple and blue colour of the latter appears. The 
solution of the oxide of osmium with pure ammonia, becomes 
somewhat yellow, and slightly so with carbonate of soda It is 
not affected by pure magnesia, nor by chalk ; but with lime a 
solution is formed, of a bright yellow colour. The solution with 
lime gives with galls a deep red precipitate, which becomes blue 
by acids. It produces no effect on a solution of platina or gold ; 
but precipitates lead of a yellowish-brown, mercury of a white, 
and muriate of tin of a brown colour. 
The oxide of osmium becomes of a dark colour with alcohol, 
and, after some time, separates in the form of black films, leaving 
the alcohol without colour. The same effect is produced by 
ether, and much more quickly. 
This oxide appears to part with its oxygen to all the metals, 
excepting gold and platina. Silver being kept in a solution of 
it for some time, acquires a black colour ; but does not entirely 
deprive it of smell. Copper, tin, zinc, and phosphorus, quickly 
produce a black or gray powder, and deprive the solution of all 
smell, and of the power of turning galls of a blue colour. This 
black powder, which consists of the osmium in a metallic state 
and the oxide of the metal employed to- precipitate it, may be 
dissolved in nitro-muriatic acid, and then becomes blue with 
infusion of galls. 
S H 2 
