308 THE ATOMIC WEIGHTS. 



metals. Accordingly, in a supplementary paper, Winkler* gives the 

 results of some check experiments made with iron, which, however, was 

 not absolutely pure. The conclusion is that the error, if existent, must 

 be very small. 



In 1895 Hempel and Thiele's work on cobalt appeared. f First, cobalt 

 oxide, prepared from carefully purified materials, was reduced in hydro- 

 gen. The weights of metal and oxygen are subjoined, with the percent- 

 age of cobalt in the oxide deduced from them : 

 Co. 



.0074 



.79159 

 1-31558 



This mean combines with former means as follows : 



Russell 78.592, ± .0023 



Zimmermann 78.635, =b .0002 



Retnmler 78.613, ± .0099 



Hempel and Thiele 78.666, ± .0074 



General mean 78.633, zh .0002 



In their next series of experiments, excluding a rejected series, Hempel 

 and Thiele weighed cobalt, converted it into anhydrous chloride, and 

 noted the gain in weight. In four of the experiments the chloride was 

 afterwards dissolved, precipitated with silver nitrate, and then the silver 

 chloride was weighed. The data are as follows : 



*Zeitsch. Anorg. Chem.., 8, 291. 1S95. 

 tZeitsch. Anorg. Chem., 11, 73. 



