FLUORIC ACID, 8$ 



fact, which, I believe, was before observed by Scheele, without 

 attempting an explanation of it. It may, perhaps be said, that 

 as the water evaporates, the affinity of the subsilicated fluat for 

 «ilex increases. 



Subsilicated fluat of ammonia is decomposed by the sulphuric I* decomposed 

 acid, and by muriatic acid gas, and also by the fixed alkalies a Jd"andatka- 

 and by ammonia. lies. 



Sulphuric acid expels from it, silicated fluoric gas and hy- Effects of sul- 

 drated fluoric acid fumes. ■**# acid ' 



Muriatic acid gas acts slowly on it, and effects its decomposi- and muriatic 

 tion apparently through the medium of its water. A little aci ga8 * 

 of the crystalline salt was introduced into muriatic acid gas in 

 a jar over mercury. In a short time, some silicated gas was 

 produced, as the silicious deposition, on the addition of water, 

 indicated. Strong muriatic acid was substituted for the acid 

 gas. Now no apparent change took place, for on evaporating M«k{jtic idii 

 the acid, the residue, decomposed by sulphuric acid, afforded no change : 

 only silicated flucric acid gas. 



The alkahes form by the decomposition of this salt, the same Alkalies form- 

 compounds that they do by their action on subsilicated fluoric tne same salts 



as with the 

 ■acid. _ subsilicated 



Potash expels the ammonia, and produces the silicated fluat aci«l. 

 and fluat of potash, as MM. Gay Lussac and Thenard have 

 described . 



The changes occasioned by soda appeared to me similar : 

 but the gentlemen just mentioned, assert that this alkali preci- 

 pitates the whole of the silex, and does not form a triple salt 

 with it and part of the acid. 



Ammonia seems to me to separate completely the silex, and Ammonia 

 by uniting with the pure acid to constitute a true fluat. MM. completely •* 

 Gay Lussac and Thenard are of a different opinion. They j ex , 

 say that the whole of the silex cannot by this method be re- 

 moved, but only the principal part. Their reason for this 

 belief, is, that on repeatedly evaporating the salt after the addi- 

 tion of ammonia and re-dissolving it, they have each time ob- 

 served a residue of silex. If they employed metallic evaporating 

 vessels, the results of my experiments do not agree with theirs ; 

 for making use of platina for this purpose, and adding an ex- 

 cess of ammonia, I never detected traces of silex on evaporating 

 the filtered fluat. But our results agree, if they employed glass 



or 



