606 FLUORIC PRINCIPLE. 



phuric acid. It requires a heat above 212 to make it boil, and it 

 condenses again in striae ; it chars animal and vegetable substances 

 like the sulphuric acid; it blackens paper, and forms a true ether 

 with alcohol. On glass it has no effect, its affinity for silica being evi- 

 dently supplanted by that of the boracic acid. 



(g.) It unites with ammoniacal gas in 3 proportions ; in equal 

 measures, if the ammonia be first introduced into the tube ; the com- 

 pound is then solid and neutral ; if the fluo-boric gas pass in by bub- 

 bles, the combination is liquid, and in the proportion of 2 ammonia to 

 1 of the acid gas. If to this last more fluo-boric gas be admitted, it 

 is absorbed and the product still remains liquid. Heat expels part 

 of the ammonia from both the fluid compounds, and a solid, volatile 

 &n4 unaltered by heat, is obtained.* 



Nature of the fluoric principles. 



1. REMARK. Three acids, the boracic, the fluoric and the muri- 

 atic, were, for many years, mentioned in connexion, as undecomposed 

 bodies. The boracic, as we have seen, has been satisfactorily de- 

 composed, and the analysis has been confirmed by synthesis. Its 

 constitution is in perfect accordance with that of most of the other 

 acids, as it consists of a combustible base and oxygen.. The muriatic 

 acid, as we shall soon see, is now regarded, by the chemical world, 

 as a compound of an inflammable basis, namely, hydrogen, not how- 

 ever with oxygen, but with chlorine, which is admitted as a principle 

 analogous to oxygen, fluoric remains for 



2. COMPOSITION OF FLUORIC ACID. In the researches of Sir H. 

 Davy, of Gay-Lussac andThenard, and of Berzelius, maybe found 

 most of the facts relating to this investigation. It would occupy too 

 much room to recite them here in detail. f Potassium and sodium 

 can both be made to burn vividly in fluo-boric and fluo-silicic acid 

 gas, and a combustible substance makes its appearance, but it is evi- 

 dently the basis of the boracic acid in the first case and of silica in 

 the second j and accordingly, when they are, respectively, made to 

 burn in oxygen gas, boracic acid and silica are reproduced. Those 

 experiments may therefore be regarded as affording a convenient 

 method of decomposing boracic acid and silica ; and in that view 

 they are valuble, and the method by fluo-silicic gas or the fluo-silicate 

 of soda and potassa is the most valuable one which we possess for 

 obtaining the basis of silica. (See p. 277.) Potassium, as already 

 stated, burns vividly, and even with explosion, in the strongest liquid 

 fluoric acid that has hitherto been obtained. As that fluid is always 



* Henry, Vol. I, p. 366. 



t See Recherches Physico-Chimiques, Tom. II, Phil. Trans, for 1813 and 1814, 



d the scientific journals of the day. 



