the Decomposition of the Earths, &c. 365 
of the metals without the aid of a new combination, we may 
expect that this result will be afforded by the most volatile 
and oxidable, such as arsenic, or the metals of the fixed 
alkalies, submitted to intense heat, under electrical polarities, 
and having the pressure of the atmosphere removed. 
Whatever new lights new discoveries may throw upon 
this subject, still the facts that have been advanced, shew that 
a step nearer at least has been attained towards the true 
knowledge of the nature of the alkalies and the earths.* 
* Since the facts in this Paper were communicated to the Royal Society, I have 
seen an account of some very curious experiments of M.M. Gay Lussac, and 
Thenasd, (in Number 148 of the Moniteur, for 1808, which I have just received,) 
from one of which they have concluded, that potassium may be a compound of 
hydrogene and potash.” 
These gentlemen are said to have heated potassium in ammonia, and found that 
the ammonia was absorbed, and that hydrogene gas equal to two-thirds of its 
volume appeared, and that the potassium by this process had become of a grayish- 
green colour. By heating this grayish-green substance considerably, two-fifths of the 
ammonia were again emitted, with a quantity of hydrogene and nitrogene correspond- 
ing to one-fifth more, and by adding water to the mixture, and heating it very strongly 
again, they obtained the remainder of the ammonia, and nothing but potash was left. 
In these complex processes, the phaenomena may be as easily explained on the idea 
of potassium being a simple, as that of its being a compound substance; nor when 
the facts that have been stated in this paper and those about to be stated, are con- 
sidered, can the view of these distinguished chemists, as detailed in the notice referred 
to, be at all admitted. 
Potash, as I have found by numerous experiments, has no affinity for ammonia, for 
it does not absorb it when heated in it; it is not therefore (allowing their theory) 
possible to conceive that a substance having no attraction for potash, should repel 
from it a substance which is intimately combined with it, and which can be separated 
in no other way. 
A part of ihe hydrogene evolved in their experiment, may be furnished by water 
contained in the ammonia; but it is scarcely possible that the whole of it can be 
derived from this source, for on such an idea the ammonia must contain more than half 
its weight of water. There is however no evidence that the whole of the hydrogene may 
