which becomes a violet coloured Gas by Heat. 77 
Conceiving from the action of potassa upon it, that it must 
be a compound of the peculiar substance and silver, I endea- 
voured to form it directly by the combination of the two bodies. 
I introduced some of the substance into the closed end of a 
small glass curved tube, and placed in the upper part of it 
some silver foil; I heated the foil nearly to redness, and then 
passed the substance over it in vapour ; there v/as an imme- 
diate action, the silver was rapidly dissolved, and a fusible 
substance formed, in all its obvious sensible and chemical 
characters, the same as that obtained from solutions of the 
substance by nitrate of silver. 
The modes which occurred to me, as most likely to effect 
its decomposition by chemical agents, were the action of the 
highly inflammable metals upon it which unite to oxygen and 
chlorine, or the action of chlorine which in general tends to 
the expulsion of oxygen, and to the separation of inflammable 
bases from that principle. 
I heated some potassium in a little glass tube, and passed 
some of the substance in vapour over it; at the moment the 
vapour came in contact with the potassium, there was an in- 
flammation, and the potassium burnt slowly with a pale blue 
light. There was no gas disengaged when the experiment 
was repeated in a mercurial apparatus. 
The substance formed by the action of potassium was wdiite, 
fusible at a red heat, and soluble in water. It had a peculiar 
acrid taste. When acted upon by sulphuric acid, it effervesced, 
and the peculiar substance appeared. 
It was evident that in this experiment there had been no 
decomposition of the body ; the result seemed to depend merely 
upon the combination of it with the potassium. 
