182 FLUORIC ACID AND ITS COMPOUNDS. 



I atom fluoboric acid 4-25 



II atom ammonia 3* 1875 



So that an integrant particle of it weighs 7*4375. 



The property which the neutral fluoborate of 

 ammonia has to lose half of its ammonia when 

 exposed to the air, and of being converted into 

 a bisalt, is analogous to what happens to other 

 ammoniacal salts. Thus when neutral carbonate 

 of ammonia is exposed to the air in powder, 

 one-half of the ammonia flies off, and a bicar- 

 bonate of ammonia remains. 



It was shown in the seventh chapter of this trea- 

 tise, that we obtain the specific gravity of most 

 gases if we multiply their atomic weight by 

 0*5555 (= half the specific gravity of oxygen 

 gas). This law holds in the present case. For 



4-25 X 0-5555 = 2-3611, 



a number which only differs by 2okoth part from 

 the specific gravity obtained by experiment. 

 This coincidence is too near to leave any doubt 

 that 2-36li is the true specific gravity of flu- 

 boric acid gas. 



In this chapter I have taken no notice of the 

 hypothesis originally started by M. Ampere, and 

 so ably supported by Sir H. Davy, that fluoric 

 acid is a compound of equal volumes of hydro- 



