86 An Account of some -new Experiments 



portions of hydrogen to one of fluorine, the true composition of 

 fluate of ammonia will be one proportion of fluoric acid oo, and 

 two proportions of atnnionia 64 "■'. 



The volatility of flviate of ammonia rendered it impossible to 

 ascertain l^y evapora.tion the real quantity of solid salt formed : 

 though the heat was never raised so high as that of boiling 

 water, yet only 12v grains of solid fluate of ammonia could be 

 procured. 



Two hundred cubical indies of ammonia, which weigh 36 

 grains, condense one hundred cubical inches of silicated fluoric 

 gas, weighing, under the saine circumstances, 110'7; and if it 

 be supposed that silicated fluate of ammonia contains one pro- 

 portion of silicated fiuoiic acid and one of ammonia, then the 

 number representing silicated fluoric gas will be 98'4, and it 

 may be conceived to consist of two proportions of fluorine 6G, 

 and one of the siliceous basis 32-4. 



According to the experiments of John Davy, 100 parts of si- 

 licated fluoric acid afl'ord G 1 "4 of silica when decomposed by 

 aqueous solution of ammonia : hence silica may be conceived to 

 consist of 32*4 of basis and 29 of oxygen, and this is very near 

 two proportions of oxygen. 



I decomposed 20 grains of silicated fluate of ammonia by so- 

 lution of ammonia, and I obtained 9-2 grains of silica. This 

 result offers proportions very little different from those gained 

 in tlie preceding calculations. 



I have made some direct experiments with the hopes of de- 

 termining the proportions of oxygen in silica; but they have been 

 unsuccessful. I have ascertained, however, that it requires more 

 than three parts of potassium to deccmjjose one part of silica ; 

 which shows that this substance cannot contain much less than 

 half its weight of oxygen. 



I have endeavoured to separate the siliceous basis in a pure 

 form, with the view of making synthetical experiments on its 

 nature by combustion in oxygen ; and my results, though not 

 perfectly" satisfactory, yet seem worthy of notice, and may lead 

 to more successful attempts. 



I decomposed silica by passing potassium in excess through 

 it, in a heated tube of platinum : the result consisted chiefly of 

 alkali containing a dark-coloured powder, the basis of silica 

 diffused through it. I fused the whole mass with sulphur, 

 which, in coml)iuing with the dry alkali, produced ignition. I 

 attempted to detach the su'phuret of potassa by water : in this 

 case the dark particles separated ; but during their separation, 

 and after, they acted upon the water of the solution producing 



•* Tliat is, if ariimoiiia be regarded as composed of one proportion of 

 azote 26, and six of iiydrogen. 



gas. 



