$02 Mr. J. Davy’s Account of some Experiments 
attempting an explanation of it. It may perhaps be said, that 
as the water evaporates, the affinity of the subsilicated fluat for 
silex increases. 
Subsilicated fluat of ammonia is decomposed by the sulphu- 
ric acid, and by muriatic acid gas, and also by the fixed alkalies 
and by ammonia. 
Sulphuric acid expels from it, silicated fluoric gas and hy- 
drated fluoric acid fumes. 
Muriatic acid gas acts slowly on it, and effects its decom- 
position apparently through the medium of its water. A little 
of the crystalline salt was introduced into muriatic acid gas in 
ajar over mercury. In a short time some silicated gas was 
produced, as the silicious deposition, on the addition of water, 
indicated. Strong muriatic acid was substituted for the acid 
gas. Now no apparent change took place, for on evaporating 
the acid, the residue, decomposed by sulphuric acid, afforded 
only silicated fluoric acid gas. 
The alkalies form by the decomposition of this salt, the same 
compounds that they do by their action on subsilicated fluoric 
acid. 
Potash expels the ammonia, and produces the silicated fluat 
and fluat of potash, as M. M. Gay Lussac and Thenard have 
described. 
The changes occasioned by soda appeared to me similar; 
but the gentlemen just mentioned, assert that this alkali preci- 
pitates the whole of the silex, and does not form a triple salt 
with it and part of the acid. 
Ammonia seems to me to separate completely the silex, and 
by uniting with the pure acid to constitute a true fluat. MM. 
Gay Lussac and Thenard are of a different opinion. They 
