94 An Account of some new Experiments 



charcoal ; but dry fluate of lead may be fused in ammonia with- 

 out undeigoing the slightest alteration; and the presence of wa- 

 ter, which may furnish oxygen to the lead and hydrogen to th« 

 fluoric principle, seem^ alisolutely i cessar^ for the production 

 of oxidated bodies from the fluoric combination*. 



I obtained analos:ous results by t;cting on siiicated fluate of 

 ammonia and fluo-borate of ammonia by chlorine : when the 

 salts were nioist, or when the gas was not free from vapour, si- 

 lica and boracic acid were formed in small quantities ; but when 

 water was carefully excluded, these bodies did not appear; and 

 the results were muriate of ammonia and siiicated fluoric gas, 

 or fluo-boric gas and azote. 



I ignited two points of charcoal intensely in fluo-boric and 

 siiicated fluoric acid gases, pure, and mixed with oxygen ; but 

 no change, indicating a decomposition, took place ; the only 

 new product was a little inflammable gas, which was probably 

 disengaged from the charcoal. 



I passed pure li<juid fluoric acid over charcoal ignited to white- 

 ness, in a platinum tube ; no carbonic acid was formed, and a 

 very minute quantity of gas only was produced, which proved to 

 be hydrogen. 



I mentioned in my last communication to the Society, that 

 I had made several experiments on the composition of the 

 fluates : since that time I have repeated some of the processes, 

 and I shall detail such of the results as appear to be most cor- 

 rect. In experiments on the fluates, it is very difficult to ex- 

 clude sources of inaccuracy ; glass vessels cannot be used, and 

 even silver and platinum vessels are slightly acted upon by the 

 pure fluoric combinations soluble in water. 



Fluor spar decomposed by sulphuric acid increases more than 

 three-fourths of its original weight ; but to produce this result 

 several successive distillations of it with fresh portions of acid 

 are necessary, and the spar must be in very fine powder, and the 

 result must be powdered after every operation. 



In an experiment made in a crucible of platinum, in which 

 very pure white Derbyshire spar was used, and sulphuric acid 

 distilled in glass vessels, and in which the product was heated 

 to whiteness in every operation, 100 grains became in the first 

 operation 1 5 9'4 grains, which gained 



in the second 6*9 



in the third 4*2 



in the fourth l'& 



in the fifth 1-6 



in the sixth 0-9 



in the seventh 0*3 



in the eighth -'0, 



Total increase 75 '2 If 



