SSG Account of some Experiments 



that which strong muriatic acid does, and it has a very 

 similar effect on the cuticle. It does not appear to erode 

 glass, for 1 have kept it in bottles of ihis substance more 

 than a month without any action being perceptible. Ex- 

 posed to the air, it slowly and almost completelv evaporates, 

 there being only a very trifling siliceous residue; and when 

 gently heated in an open yessei, it is rapidly dissipated in 

 white fumes. 



S'Ecr. ir. On the Comhinat'ions of S'dkated Fluoric Acid 

 Gas, and the Suhsiticated Fluoric, and the Fbioric Acids 

 with Ammonia. 



M. Gay Lussac has shown that silicated fluoric acid gas, 

 like carbonic acid gas, condenses twice its volume of the 

 vola'ile alkali*. The experiment 1 have several times re- 

 peated, and constantly with the same result, no diflerence 

 appearing when the acid gas was added in great excess to 

 the alkaline, or the alkaline to the acid. This beuig the 

 case, and knowing the specific gravities of the two gases f, 

 100 par^s by weight of silicated fluat of ammonia seem to 

 consist of 24'5 ammonia 



755 acid 



1000 

 Silicated fluat of ammonia volatilizes unaltered, if heated 

 by a spirit-lamp in the vessel in which it is formed, and 

 provided moisture be entirely excluded. 



Like silicated fluoric acid gas itself, this salt is decom- 

 posed by water, and a similar precipitation of silex occurs, 

 «nd in the same proportion. Thus the salt formed by the 

 union -of 30 cubic inches of silicated fluoric gas, and 60 

 of volatile alkali (barom. 30, therm. 6o) in a small glass 

 jar over mercury, being carefully collected and introduced 

 into water, afforded five grains of pure silex, weighed after 

 being well washed and heated to redness. 



The saline solution, since part of the silex of the silicated 

 fluoric acid gas is separated during its production, appears 

 to be a subsiticated fluat, or a combination of subsilicated 

 fluoric acid and ammonia. Another mode of making it, 

 more directly proves that this is its composition. When 

 ammonia is added to the subsilicated fluoric acid in excess, 

 this salt is formed without any precipiiatioii. From these 



* vide Mem. d'Arniril, tome ii. 



f According to Sir H. Davy, 100 cubic inches of ammonia, barom. 30, 

 therm. 60, ■weigh 18 grains. It is this estimate which I have taken. 



f^cts. 



