408 Experiments on the Substances produced 
spect, as they supposed that no part. of the inflammable 
matter was derived from silica, and they likewise reasoned 
on the phenomena with more caution. 
At the time that my conclusions were drawn, I was ig- 
norant of the true nature of the muriatic acid. After I had 
tried in vain to decompose oxymuriatic gas, and after I had 
found that the compounds of this substance with phos- 
phorus, sulphur, and the metals combined with ammonia 
without any decomposition, and produced compounds in 
which no oxygen could be discovered ;_ I was forcibly struck 
by the analogy between the oxymuriatic and the fluoric 
compounds, and led to doubt of the justness of my ideas 
respecting the nature of fluoric acid. 
I tried an experiment on the comparative quantities of 
fluate of lime, formed from equal volumes of silicated flu- 
oric acid gas, one of which had been acted upon by potas- 
sium, and then exposed to solution of ammonia, the other 
had been absorbed by solution of ammonia: and I found 
the proportion of calcareous fluate nearly one-third larger 
in the latter case. This result at first seemed favourable to. 
my early ideas, that the acid contained a peculiar inflam- 
mable basis, which was separated by the potassium, and 
existed in the combustible substance insoluble in waters 
but it could not be considered as decisive on the question ; 
for it occurred to me.as possible, that this substance might 
be silicum, or the basis of silica united to a much smaller 
proportion of the fluoric principle than that existing in sili- 
cated fluoric acid. 
During the period that I was engaged in these imvestiga- 
tions, I received two letters from M. Ampere, of Paris, 
containing many ingenious and origina: arguments in fa- 
vour of the analogy between the muriatic and fluoric com- 
pounds: M. Ampere communicated his views to me in 
the most liberal manner; they were formed in consequence 
of my ideas on chlorine, and supported by reasonings drawn 
from the experiments of MM. Gay-Lussac and Thenard. 
Before I enter upon the detail of the investigations which 
promise to elucidate the nature of the fluoric compounds, 
it will be right to describe those substances produced from 
fluor spar, which have been the principal objects of my ex- 
periments, and to mention the different hypothetical views 
that may be formed respecting them. 
The first of these substances is the silicated fluoric acid 
gas, which was discovered by Scheele, and examined in its 
pure state by Priestley. It is formed by heating a mixture 
of fluor spar, powdered glass, and sulphuric acid, It is a 
very 
