FLUOSILICIC ACID. 177 



This salt is a white powder, which has a saline 

 taste, pretty similar to that of sal-ammoniac. 

 When laid dry upon litmus paper it does not 

 produce any alteration, but when a drop of 

 water is added, the litmus paper becomes red. 

 Fluosilicate of ammonia dissolves in water ; but 

 flocks of silica are at the same time disengaged, 

 and the solution reddens vegetable blues. 

 Hence, it is obvious, that water has the property 

 of destroying this salt by decomposing its acid. 



From the account given of fluosilicic acid in 

 the preceding part of this section, it is obvious, 

 that it resembles oxygen gas in the number of 

 atoms contained in a given volume of the gas ; 

 but oxygen gas contains four times as many 

 atoms in a given volume, as ammoniacal gas does. 

 It follows from this, that the fluosilicate of am- 

 monia, formed by mixing the two gases, is a 

 compound of 2 atoms fluosilicic acid, and 1 atom 

 of ammonia ; or it is a bifluosilicate of ammonia. 

 Hence, its composition and atomic weight must 

 be as follows : 



2 atoms of fluosilicic acid 6-5 

 1 atom ammonia 2-125 



8-625 



It is obviously anhydrous. I did not find that 

 one volume of fluosilicic gas was capable of con- 

 densing four volumes of ammoniacal gas. I 



VOL. II. M 



