410 Experiments on the Substantes produced 
Three hypotheses may, according to sound analogies, be 
formed on the nature of the fluoric combinations. In the 
first, which is-that generally adopted, the silicated fluoric 
acid gas is supposed to be a compound of silica and a pecu- 
liar acid, itself consisting of inflammable matter and oxy- 
gen; fluo-boric acid gas, a compound of boracic acid and 
the same acid ; aud pure liquid fluoric acid as water com- 
bined with the acid. : 
In the second hypothesis, that which I have alluded to in 
the beginning of this paper, and that adopted by M. Am- 
pere, the silicated fluoric acid is conceived to consist of @ 
peculiar undecompounded principle, analogous to chlorine 
and oxygen, united to the basis of silica, or stlicum; the 
fluo-horic acid of the same principle united to boron ; and 
the pure liquid fluoric acid as this principle united to hy- 
drogen. 
In the third hypothesis, which probably would have been 
formed by the disciples of the pblogistic school of che- 
mistry, had they been acquainted with the facts, the liquid 
fuoric acid is considered as an undecompounded body ; 
and the metals and inflammable bodies as compounds of 
certain unknown bases with hydrogen: silicated fluoric 
acid gas, on this idea, must be regarded as a compound of 
the fiuoric acid with the basis of silicum, and fluo-boric acid 
gas as a compound of fluoric acid and the basis of boron. 
Whoever will consider, with attention, the different 
facts that have been brought forward by Scheele, Gay-Lussae 
and Thenard, John Davy, and myself, will find that they 
will admit of explanation on either of these hypotheses ; 
and as, in all the cases yet brought forward, of the most 
simple chemical action of other bodies on the fluoric sub- 
stances, more than one new form of matter is produced, 
no explanation of the phenomena can at present be given 
without involving suppositions. : 
It is not easy te devise simple experiments to ascertain 
which of these hypotheses is true; yet, in admitting strict 
analogical reasoning, it is easy to show which is most con- 
formable to the general series of chemical facts. 
Those acids which are known by direct experiments of 
decomposition by heat, to consist of oxygen, bases, and 
water, such as the strongest sulphuric and nitric acids and 
hydro-phosphorous acid, when they are acted on by am- 
monia, afford moisture: this is easily proved, by causing 
them to absorb ammoniacal gas in glass retorts, and gently 
heating the mixture; when water immediately appears. On 
this view, it occurred to me, if the liquid fluoric acid was 
a com~ 
