176 FLUORIC ACID AND ITS C OMPOUNDS, 



2*006 approaches so nearly to 2, the atomic 

 weight of silica, that we can have no hesitation 

 in considering fluosilicic acid as a compound of 

 1 atom fluoric acid and 1 atom silica; hence, its 

 atomic weight is 3*25. 



It was shown in the seventh chapter of this 

 work, that if we multiply the atomic weight of a 

 gaseous body by 1-1111 (the specific gravity of 

 oxygen gas) or 0-5555, (half the specific gravity 

 of oxygen gas) or by 0-2777 (*th of that specific 

 gravity) we obtain the specific gravity of the 

 gaseous body so multiplied. Now, 3-25 x 

 1'llli = 3-6lli. This number approaches so 

 nearly the specific gravity of fluosilicic acid de- 

 termined experimentally, as to leave no doubt 

 that it represents the true specific gravity of this 

 gas. 



The specific gravity of fluosilicic acid gas, 

 then, is 3*6lli, and its atomic weight 3*25, and 

 it is a compound of 1 atom fluoric acid and 1 

 atom silica. 



As this gas is decomposed when it comes in 

 contact with water, there are very few of its sa- 

 line combinations which we have it in our power 

 to form ; for the dry bases, as far as my trials 

 went, did not exhibit any disposition to absorb 

 it. When one volume of fluosilicic acid gas is 

 mixed with two volumes of ammoniacal gas, 

 they condense each other into a white solid salt, 

 which is obviously a fluosilicate of ammonia. 



