274 ■ "^'^ H. Davy on the Substances produced 



principle from the siliceous basis, or to form a triple com- 

 pound, from which silicated fluoric acid gas is capable of being 

 reproduced, in consequence of the combination of a part of the 

 potassium and siliceous basis with oxygen ; and on this idea 

 the cause of the apparent loss of the fluoric principle, in the 

 experiments on the action of ammonia on the product of the 

 combustion of potassium in silicated fluoric acid gas, becomes 

 obvious. 



Assuming then from the analogy with chlorine, that the dif- 

 ferent fluoric compounds consist of inflammable bodies united 

 to a peculiar principle, it follows that all attempts to decompose 

 the fluoric acids, by combustible substances, can lead to no 

 other result, than that of occasioning new combinations of the 

 fluoric principle ; and the only methods which seemed plau- 

 sible for obtaining this principle pure, after that by electrical 

 decomposition had failed, were by the action of oxygen or 

 chlorine on certain of its compounds. Chlorine is, in certain 

 instances, detached from hydrogen by oxygen ; and oxygen, 

 in a number of cases, is detached from metals by chlorine ; I 

 thought it therefore probable, that the fluoric principle might, 

 in some process, be separated from bases by either chlorine 

 or oxygen. 



In selecting compounds for experiments of this kind, I was 

 guided by the relative attractions of the fluoric and muriatic 

 acids, of chlorine and oxygen. Horn silver and calomel, and 

 muriate of potassa are not decomposed by fluoric acid, but 

 fluate of silver, of mercury, and of potassa are easily decom- 

 posed by muriatic acid; I therefore conceived, that the fluoric 

 principle would most likely be expelled from the dry fluates 

 of silver, mercury, and potassa by chlorine. 



