ZINC, CADMIUM, LEAD, &c. 



27 j it' we reckon the atomic weight of mercury 

 25. The truth of this is sufficiently established 

 by the following experiment. 



menteof ^ grain s of pure peroxide of mercury, pre- 

 the author, pared on purpose for the experiment, were put 

 into an eight-ounce phial, and as much muriatic 

 acid poured upon it as dissolved it completely. 

 The phial was then placed upon the sand bath 

 (having a charcoal stopper fitted into its mouth), 

 and left till the liquid was evaporated to dryness. 

 The phial was then covered about two-thirds up 

 with sand, and the temperature was gradually 

 raised sufficiently high to sublime the corrosive 

 sublimate, into which the red oxide had been 

 converted, as high as the middle of the phial. 

 The phial, after being allowed to cool gradually, 

 was weighed, and the weight of the corrosive 

 sublimate was exactly 34 grains. 



From this experiment it appears, that 27 per- 

 oxide of mercury form exactly 34 corrosive sub- 

 limate. 



To understand this experiment it is necessary 

 to know, that mercury combines with two pro- 

 portions of chlorine, and forms two chlorides. 

 The protochloride, usually denominated calomel, 

 is a compound of 1 atom mercury and 1 atom 

 chlorine ; while the perchloride, or corrosive sub- 

 limate, is a compound of 1 atom mercury and 2 

 atoms chlorine. 



With the knowledge of these facts, we may 



