85 
on the Nature of certain Bodies. 
and from their general powers of combination, and from the 
conducting nature and lustre of the matter produced by the 
action of a small quantity of potassium upon the olive coloured 
substance, and from all analogy ; there is strong reason to 
consider the boracic basis as metallic in its nature, and I ven- 
ture to propose for it the name of boracium. 
7. Analytical Inquiries respecting Fluoric Acid. 
I have already laid before the Society, the account of my 
first experiments on the action of potassium, on fluoric acid 
gas.* 
I stated, that the metal burns when heated in this elastic 
fluid, and that there is a great absorption of the gas. 
Since the time that this communication was made, I have 
carried on various processes, with the view of ascertaining, 
accurately, the products of combustion, and I shall now de- 
scribe their results. 
When fluoric acid gas, that has been procured in contact 
with glass, is introduced into a plate glass retort, exhausted 
after being filled with hydrogene gas, white fumes are imme- 
diately perceived. The metal loses its splendour, and be- 
comes covered with a grayish crust. 
When the bottom of the retort is gently heated, the fumes 
become more copious ; they continue for some time to be 
emitted, but at last cease altogether. 
* Phii. Trans. Part IT. 1808, p. 343. The combustion cf potasshim in fluoric acid, 
I h:ve since seen mentioned in the number of the iVionheur, already so often quoted, 
as observed by M. M. Gay Lussac and Thehard; but no noace is taken of the 
results. 
