Mr. Davy’s Experiments on 
contact with solid potash, an alloy of arsenic and potassium 
was formed of a dark gray colour, and perfectly metallic ; it 
gave off'arseniuretted hydrogene by the action of w r ater with 
inflammation, and deposited a brown powder. 
When potassium and arsenic* were heated together in hy- 
drogene gas, they combined with such violence as to produce 
the phenomena of inflammation, and an alloy was produced of 
the same kind as that formed by means of the Voltaic battery. 
As tellurium and arsenic both combine with hydrogene, it 
appeared to me probable, that by the action of alloys of po- 
tassium, with tellurium and arsenic, upon ammonia, some 
new phenomena would be obtained, and probably, still fur- 
ther proofs of the decomposition of the volatile alkali, in this 
process afforded ; and this I found w’as actually the case. 
When the easily fusible alloy of tellurium with potassium, 
in small quantity, was heated in ammonia, the surface lost its 
metallic splendour, and a dark brown matter was formed, 
which gave ammonia by exposure to air ; and the elastic fluid, 
which was generated in this operation, consisted of four-sixths 
nitrogene, instead of being pure hydrogene, as in the case of 
the action of potassium arine. 
The alloy of arsenic and potassium, by its action upon 
* In reasoning upon the curious experiment of Ca det, of the production of a volatile 
pyrophorus by the distillation of acetite of potash, and white oxide of arsenic, Four- 
croy Connais. Chem. Tom. viii. p. 197, I conceived it probable, that this pyrophorus 
was a volatile alloy o f potassium and arsenic. But from a repetition of the process I 
find, that though potash is decompounded in this operation, yet that the volatile 
substance is not an alloy of potassium, but contains charcoal and arsenic, probably 
with hydrogene. The gasses not absorbable by water given off in this operation, are 
peculiar. Their smell is intensely fcetid. They are inflammable, and seem to contain 
charcoal, arsenic, and hydrogene : whether they are mixtures of various gasses, or a 
single compound, I am not at present able to decide. 
