MERCURY. 423 



zelius 5 laboratory on the composition of the 

 oxides of mercury, with the results of which 

 only I am acquainted.* He found the constitu- 

 ents of protoxide of mercury 



Mercury . 100 or 25-063 



Oxygen . 3-99 - 1 



and those of red oxide 



Mercury . 100 or 25-031 



Oxygen . 7'99 - 2 



If we take the mean of these two analyses, which 

 do not exactly agree with each other, though 

 they come much nearer than those of Donovan, 

 we obtain 25-047 for the atomic weight of mer- 

 cury, which exceeds 25 by less than jioth part. 



Now, as the atomic weight of mercury, as de- 

 duced from Donovan's experiments, is only a 

 very little less than 25, while the same weight, 

 deduced from the experiments of Sefstrom, is a 

 very little more than 25, the inference from 

 these experiments seems to be, that an atom of 

 mercury weighs exactly 25. 



2. The experiments of Donovan and Sefstrom 

 leave no doubt that the oxygen in the peroxide 

 of mercury is just double that in the protoxide. 

 It is, therefore, composed of 1 atom mercury 

 and 2 atoms oxygen ; and its atomic weight is 



Annals of Philosophy, III. 355. 

 Dd4- 



