FLUORIC ACID. 83 



Previous to its analysis, it was necessary to ascertain the Common Cor 



specific gravity of the gas. This I have endeavoured to do. s ^f^ t -^ cs 



The gas, the subject of experiment, was quite pure, being total- heavier than 



ly condensed by water. A Florence flask was exhausted ; j Q water - 



this state, weighed by a very delicate balance, it was 



= 1452*2 grains. 



Filled with common air - = 1452*2 -"- 10*2 



Again exhausted = 1452*2 



Filled with silicated fluoric gas = 1452-2 +36*45 



Hence as 10*2 : 31 : : 36*45 : : 110 78 



Thus it appears, that 100 cubic inches of silicated fluoric acid 



gas, at ordinary temperature and pressure, are equal to 1 10*78 



grains. 



When silicated fluoric acid gas is condensed by water, it is . Bv pwcipitat- 

 ° w . ing thesilexby 



well known that part only of the silex is deposited. To ob- wa ter and 



tain the whole, in order to ascertain the proportion in the gas, am on*a, the 

 ti 11 •• ^^ L --i/-i gas was found 



I have employed ammonia in excess. 40 cubic inches of the to contain 5 



gas (barom. 30, therm. 60) were transferred in portions of P a, ; t3 acid and 



10 cubic inches at a time to a solution of ammonia. The silex 



precipitated was carefully collected on a filter, and washed 



till the water that passed through it, ceased to be affected by 



nitrate of lime. It was next dried, and strongly heated in a 



platioa crucible. It weighed 27'2 grains, and was pure silex. 



Supposing fluoric acid to be the remaining 171 grains, which 



adde*d to 27*2 giains are equivalent to the weight of 40 cubic 



inches of the gas, it appears that 100 parts by weight of this 



gas consist of 



6l*4 silex 

 38*6 fluoric acid 



1000 



That this estimate may be correct, it is evident* that am- 

 monia should have the property of precipitating the whole of 

 the silex of silicated fluoric gas j which I shall not now en- 

 deavour to prove, but leave it to be considered in another part 

 of the paper. 



There is no improbability attached to the idea, that silicated The gas con« 

 fluoric acid gas may, from the manner in which it is prepared, 2££ D ° - 

 contain a proportion of alkali. To discover whether this was 



G 2 the 



