ATOMIC WEIGHTS 



253 



The direct ratio between silver and mercury was determined by tlirow- 

 ing down the two metals, simultaneously, in the same electric current. 

 Both metals were taken in double cyanide solution. With Hardin's 

 equivalent weights I give a third column, showing the quantity of mer- 

 cury corresponding to 100 parts of silver. Many experiments were re- 

 jected, and only the following seven are published by the author : 



Mean, 92.660, ± .0051 



Hence Hg= 199.923. 



The determinations by Easley ' are quite unlike those made by his 

 predecessors. First, mercuric chloride in solution was reduced to metal 

 by means of hydrogen dioxide, and was precipitated partly as a globule 

 and partly in finely divided form. The globule was washed with water 

 and acetone and weighed. The finely divided mercury was again dissolved, 

 and with a little mercury remaining in solution, was deposited electrolytic- 

 ally upon a gold cathode. Its weight was then added to that of the 

 globule. The following results, with vacuum weights, were obtained : 



Mean, 73.8695, ± .0012 



Hence Hg = 200.478. 



Combining this with the earlier determinations we have- 

 Turner 73.791, ± .0050 



Millon 73.845, ±: .0100 



Svanberg 73.795, ± .0060 



Hardin 73.829, ±.0012 



Easley 73.8695, ± .0012 



General mean 73.8459, ± .0008 



Journ. Amer. Chem. Soc, 31, 1207 



17 



