54 DECOMPOSITION OF FLtJORIC AClB. 



experience, to be an excellent remedy agaimt comraeS. 

 burns. 

 Action of this It may readily be supposed, that we did not neglect to 

 j qui on po - pj ace suc j 1 au ac ti ve liquid in contact with the metal of 

 potash. This experiment was made in a copper tube. At 

 first we threw a piece the sfee of a small hazel nut into 

 a small quantity of this liquid ; and immediately a very loud 

 detonation ensued, with a great evolution of light and heat. 

 Afterward, desirous of knowing what was the cause of these 

 phenomena, we caused the fluid to arrive at the metal 

 gradually. In this way but little heat is produced, and we 

 could collect the products of the experiment. These pro- 

 ducts were hidrogen, fluate of potash, and water. Con- 

 sequently this active liquid is a compound of fluoric acid 

 and water. 

 It combines We see then, that this acid tends to combine with all 



stances, and is substances, and that it forms with them solid, liquid, or 

 the strongest gaseous compounds, according as it retains more or less 

 s " elasticity, or expansive force. It is the only acid with which 



this is the case : and this property is even a proof, that it is 

 the strongest and most active of acids. 

 Fluoric acid Since we cannot in any way obtain fluoric acid pure, we 



not obtainable ^ , study it when in combination with some substance, 

 pure. • • . ... 



We must take it then combined with this or that substance, 



according to the result we wish to obtain. 



Siliceous fluoric If the object be to unite it with alkalis, earths-, or me-* 



acid forms tri- . , , , „ , .... 



pte salts with tallic oxides, we must be careful not to employ siliceous 



alkalis, earths, fl uor i c acid, for in this case we should obtain triple salts. 

 Thus, on pouring ammonia into acid fluate of silex, we 

 obtain a triple salt nearly insoluble, yet in great measure 

 volatile. Thus too, on pouring muriate of barytes into 

 acid fluate of silex, we obtain after some time a crystalline 

 precipitate, insoluble in a great excess of nitric acid, which 

 might be mistaken for sulphate of barytes, and is nothing 

 but fluate of silex and barytes. 

 For decompo- But when, instead of wanting to combine fluoric acid 

 should 1 be wii- w '^ these substances, we wish to decompose it, as we pur- 

 ployed, posed to do by means of the metal of potash, it is evident, 

 that we ought not to emplo^ liquid fluoric acid, on account 

 of the water present with it; and that we should prefer, ei- 

 ther 



