“Abo On Iridium and Osmium. (Dec. 
to melt, assuming a very beautiful and intense green colour. “At 
last it dissolved entirely, and formed a small quantity of a brown* 
ish-red liquid. The solution of potash assumed a yellow colour, 
and an odour of osmium mixed with that of oxymuriatie acid, 
When I opened the flagon containing the solution of which I 
have just spoken, there issued out a dense white vapour, having ari 
insupportable odour of osmium and oxymuriatic acid. To be able 
to separate this liquid from the flagon without losing much of it, I 
mixed it with a quantity of water, and subjected it to the following 
experiments. 
L. A drop or two of this solution let fall into a glass of water, 
assumed a very deep blue colour on adding infusion of nutgalls. 
2. When a plate of zinc was put into the solution, it soon passed 
to blue, and black flocks precipitated. 
I may remark, that the green colour analogous to that of oxide 
of chromium, which the osmium assumed at the instant of its solu- 
tion, may proceed from a mixture of the liquid, which is reddish- 
yellow, with a portion of the metal which I suppose to be blue. 
And, in fact, in proportion as the solution goes on, the green 
‘colour becomes weaker and disappears entirely, to give place to 
reddish-yellow. 
When osmium is mixed with water, in order to be dissolved in 
oxymuriatic acid, it does not become green; but forms at once a 
yellowish-red liquid. 
If ammonia be put into this solution till the acid is saturated, a 
brown precipitate. in flocks falls down, small in quantity, and the 
liquid passes to a pure yellow, preserving the odour peculiar to 
osmium. 
This precipitate consists almost entirely of iron, coming no doubt 
from the zinc, 
Action of common Muriatic Acid and Osmium. 
Osmium dissolves in muriatic acid when assisted by a gentle heat. 
The solution begins by being green; but it soon becomes reddish- 
yellow. If tothe muriatic acid we add some drops of nitric acid, 
the solution takes place more readily, so that we scarcely perceive 
the transition from green to reddish-yellow. git 
During these solutions a great deal of osmium is always volati- 
lized, even when they are made without the assistance of heat, as 
is shown by the experiment with oxymuriatic acid. nile 
At the request of Sir H..Davy, | endeavoured, but in vain, to 
unite osmium with iodine. When the mixture of the two bodies 
was heated in a glass tube, the iodine separated in the form of 
violet vapours, which attached themselves to the upper parts of the 
tube, while the osmium remained at the bottom without having 
undergone any change. | 
~The facility with which osmium dissolves in acids, is, I conceive, 
a certain proof that in crude platinum it is united to-some substance 
~ 
