168 THE ATOMIC WEIGHTS. 



.0062 



Mean, 60.2278, dz .on 



These results give values for Co and Ni differing by less 

 than a tenth of a unit ; here, as elsewhere, the figure for Ni 

 being a trifle the lower. 



In 1863 * the idea that nickel and cobalt have equal 

 atomic weights was strengthened by the researches of Russell, 

 He found that the black oxide of cobalt, by intense heating 

 in an atmosphere of carbon dioxide, became converted into 

 a brown monoxide of constant composition. The ordinary 

 oxide of nickel, on the other hand, was shown to be convert- 

 ible into a definite monoxide by simple heating over the blast 

 lamp. The pure oxides of the two metals, thus obtained, 

 were reduced by ignition in hydrogen, and their exact com- 

 position thus ascertained. Several samples of each oxide 

 were taken, yielding the following percentages of metal : 



NiO. 



78-597 1 



78.584 Mst sample. 

 78.608 '' 

 78.581 ] 



78.589 ^ 2d sample. 



78.583 ^ 

 78.616 \ 



78.590 [3d sample. 



4th sample. 



78.588 

 78.590 ~ 

 78.594 

 78.597 

 78.588 



Mean of all, 78.593, dz .0018 



* Joum. Chem. Soc, (2,) i, 51. 



