by the Vapotir of thé Fluor Acid. 98 
light precipitate, of the fame colour, was depofited at the 
bottom. A folution of muriate of barytes being dropped 
into the blue liquor, gave a white precipitate, like regenerated 
barytic fpar, without changing the blue colour of the firft 
light precipitate, which remained like a flimy fub{tance float- 
ing on the other, nor the clear liquor: and the latter, after 
having ftood feveral years, appears as deep a blue ascan be pro- 
thiced | by ammonia from a folution of copper. The blue flime 
was found fit for a pigment, but far inferior to Pruffian blue. 
On this occafion I recollected the blue colour of lapis la- 
zuli, which Marggraf afcribes to iron, and in which Rin- 
mann found fluor acid. This ftone, after two days expofure, 
remained unattacked, and its colour unchanged. If, how- 
ever, it is clafled among the family of the zeolites, it is, at 
any rate, of a changed nature; for the latter are eafily acted 
upon by the vapour of fluor acid. 
According to Bergmann, filiceous earth is not foluble in 
pure poems acid gas; but it is obferved in common life, in 
places where ammoniacal gas as well as carbonic acid gas 
are difengaged in abundance; fuch as dunghills, gréen- 
houfes, prifons, cattle-fialls, aul foap manufactories, &c. 
that the glafs in the windows. becomes much fooner opaque 
than in apartments where that is not the cafe. The caufe of 
this is owing in part to a cruft of foreigh matter, and in part 
to actual Pee If it now be admitted that the carbonic 
acid gas has a confiderable fhare in producing the efloref- 
cence of the glafs‘In the above-mentioned places, we may 
affume this effet, under certain modifications, in regard to 
the natural eflorefeence of ftones; as it is not fo much a 
folution of the earthy bafes, as a feparation of the cryftalliné 
connection, 
Though analogical conclufioris from chemical refults are 
of little value, they have led me to the following conjeéture : 
As the fluor acid hitherto, at Jeaft as far as I know, has never 
yet been analyfed, and as its radical is unknown, I am cf 
opinion that, till fomething pofitive is learned, we may admit 
that fluor acid is not effentially different from carbonic acid 
but in the degree of oxygenation, and that they have both 
one radical, va. carbon. : 
Faq VII. 47 
