28 Dr THOMAS THOMSON on some Experiments on Gold. 



the excess of potash had been neutralized by nitric acid, nitrate 

 of silver was added to the solution, till it ceased to produce any 

 farther precipitate. The chloride of silver being collected on a 

 filter, washed, dried, and fused, weighed 34 '65 grains, equiva- 

 lent to 8'543 grains of chlorine, or 8'78 grains of muriatic acid. 

 Thus it appears, that 24'2 grains of gold, in the state of per- 

 oxide, had been combined with 8*78 grains of muriatic acid. 

 Consequently, 25 grains of gold in the state of peroxide, must be 

 united with 9' 11 grains of muriatic acid. This is only 0.14 

 grain less than 9*25, the equivalent for 2 atoms of muriatic acid. 

 From this result it is obvious, that muriate of gold is a com- 

 pound of 2 atoms muriatic acid, and 1 atom peroxide of gold. 

 The weight of the dry salt having been 42'8 grains, it is clear 

 that it must have contained 5 atoms of water, and that muriate 

 of gold is composed as follows : 



2 atoms muriatic acid, 9'25 



1 atom peroxide of gold, 28 

 5 atoms water, - 5*625 



42-875 



The precipitation of the gold by protosulphate of iron, seems 

 to show, that the gold in this salt is in the state of oxide, and 

 consequently combined, not with chlorine, but muriatic acid. It 

 is equally clear, that, in the sodium chloride of gold, that metal is 

 not oxydized, but in the metallic state, and united to chlorine. 

 Hence the reason why it is so difficult to reduce the gold from 

 the sodium chloride by heat, while it is so easy, by a very mode- 

 rate heat, to reduce the gold from the muriate. 



4. Gold furnishes a striking example of the want of coinci- 

 dence in the proportions of oxygen and chlorine, which unite 

 with bodies, and of the danger of being misled, when we infer the 



