ATOMIC WEIGHTS 427 



In 1863 ' the idea that nickel and cobalt have equal atomic weights 

 was strengthened by the researches of Eussell. 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 convertible 

 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 composition thus ascertained. Several 

 samples of each oxide were taken, yielding the following data. The 

 separate samples are indicated by lettering: 



Nickel. 



iJoiirn. Chem. Soc. (2), 1, 51. 1863. 



