on the Nature of certain Bodies. 123 



in the other phosphurets, and phosphites of potash, are 

 generated. 



As silex was always obtained during the combustion of the 

 chocolate-coloured substance obtained by lixiviation, it oc- 

 curred to me that this matter might be a result of the ope- 

 ration, and that the chocolate substance miglit be a com- 

 pound of the siliceous and fluoric bases in a low state of oxy- 

 genation, with potash ; and this idea is favoured bv some 

 trials that I made to sepaiaie silex from the mass, by l)oiling 

 it in concentrated fluoric acid ; the substance did not seem 

 to be much altered by this process, and still gave silex by 

 combustion. 



I endeavoured to decompose fluoric acid gas in a perfectly 

 drv state, and v\ hich contained no siliceous earth ; and for 

 this purpose I made a n)ixture of one hundred grains of dry 

 boracic acid, and two hundred grains of fluor spar, and 

 placed them in the bottom of an iron tube, having a stop- 

 cock and a tube of safety attached to it. 



The tube was inserted horizontally in a forge, and twenty 

 grains of potassium, in a proper iron tray, introduced into 

 that part of it where the heat was only sutTered to rise to dull 

 redness. The bottom of the tube was heated to whiteness, 

 and the acid acted upon by the heated potassium, as it was 

 generated. After the process was finished, the result in the 

 tray was examined. 



it was in some parts black, and in others of a dark brown. 

 It did not effervesce with water; and, when lixiviated, afforded 

 a dark brown combustible mass, which did not conduct 

 electricity, and which, when burnt in oxygen gas, afforded 

 boracic and fluoric acid. It dissolved with violent efferves- 

 cence in nitric acid ; but did not inflame spontaneously in 

 oxymuriatic acid gas. 



I have not as yet examined any of the other properties of 

 this substance; but I am inclined to consider it as a com- 

 pound of the olive-coloured oxide of boracium, and an oxide 

 of the fluoric basis. 



In examining the dry fluoric acid gas, procured in a prog- 

 ress similar to that which has been just described, it oave 

 very evident marks of the presence of boracic acid. 



As the. chocolate-coloured substance is permanent in wa- 

 ter, it occurred to me that it might possibly be producible 

 from concentrated rupiid fluoric acid at the netiative surface 

 in the Voltaic circuit. 



I made the experiment with platina surfaces, from a bat- 

 tery of two hundred and fifty plates of six inches, on fluoriq 

 acid the densest that could be obtained by the distillation of 



lluof 



