MERCURY. 427 



dence equally satisfactory, that the atomic weight 

 of mercury is 25. It will be proper to premise, 

 in the first place, that the cinnabar which I em- 

 ployed was not quite free from traces of silica 

 and peroxide of iron : but I made allowance for 

 these bodies, and have left them out of the re- 

 sults to avoid complicated statements as much as 

 possible. 



Nitric acid has not the property of decompos- 

 ing cinnabar, but nitromuriatic acid dissolves it 

 with rapidity, when assisted by heat. 29 grains 

 of cinnabar in powder were put into a retort, 

 along with a sufficient quantity of nitromuriatic 

 acid : the retort being placed on the sand bath, 

 a pretty strong effervescence began, and the cin- 

 nabar disappeared in a few minutes, with the ex- 

 ception of a yellow matter, which was separated. 

 This yellow matter was soft and ductile. When 

 first collected, it weighed 3*46 grains ; but being 

 left a few days exposed to the air it became hard 

 and brittle, and the weight was reduced to 3*2 

 grains. It was pure sulphur, burning all away 

 with a blue flame without leaving any resi- 

 due. 



The nitromuriatic solution was supersaturated 

 with carbonate of soda without the appearance 

 of any precipitate. It was, therefore, evaporated 

 nearly to dry ness, redissolved in water, and mixed 

 with a solution of caustic soda : the mercury 

 precipitated in the state of brownish red flocks, 



