on different Combinations of Fluoric Acid. 367 
observed that it possesses a slight degree of tenacity, so that 
it has an oily appearance when poured from one vessel to an- 
other; and similar in another respect, it possesses the pro- 
perty of charring animal and vegetable substances, and which 
the French chemists observed belonging to the gas itself. I 
have found that water condenses more of this, than it does of 
any other known gas, no less than 700 times its volume. The 
experiment was then made, barom. 30.5, therm. 50, of a 
cubic inch of water were introduced into a tube over mercury, 
and the gas, in portions of 5 cubic inches at a time, was added 
until 100 cubic inches had been absorbed, when the water was 
apparently saturated. This acid was of the specific gravity 
1.77. 
The property which sulphuric acid has of absorbing fluobo- 
racic acid gas has already been noticed. I found that -§■ cubic 
inch of sulphuric acid, of the specific gravity 1.85, condensed 
35 cubic inches of the gas, or 50 times its volume. The com- 
pound acid was strongly fuming, and appeared more tenacious 
than pure sulphuric acid, yet not nearly so much so as that 
compound of the two which distills over during the latter part 
of the operation of making fluoboracic gas. 
This latter compound has some peculiarities. It is so tena- 
cious, that it flows very slowly. It appears to be far more 
volatile than pure sulphuric acid. When poured into water, 
a dense white precipitate is formed, the exact nature of which 
I have not yet satisfactorily ascertained ; but which is not 
produced by the direct compound of sulphuric add, and the 
fluoboracic. 
