ATOMIC WEIGHTS 



435 



First in order comes Eeminler's research upon cobalt.' This chemist, 

 asking whether cobalt is homogeneous, prepared cobaltic hydroxide in 

 large quantity, and made a series of successive ammoniacal extracts from 

 it, twenty-five in all. Each extract represented a fraction, from which, by 

 a long series of operations, cobalt monoxide was prepared, and the latter 

 was reduced in hydrogen after the manner of Eussell. The actual deter- 

 minations began with the second fraction, and the data are subjoined, 

 the number of the fraction being given with eacli experiment : 



CoO. 



2 09938 



3 15021 



4 22062 



5 39011 



6 28820 



7 34304 



8 43703 



9 91477 



10 63256 



11 32728 



12 38042 



13 16580 



14 1.01607 



15 1.31635 



16 91945 



17 53100 



18 82381 



19 81139 



20 76698 



21 1.13693 



22 2.00259 



23 1.04629 



24 48954 



25 69152 



Mean, 78.613, ± .0099 



Hence Co = 58.813. 



Considered with reference to the purpose of the investigation, this 

 mean and its probable error have no real significance. But it is very 

 close to the means of other experimenters, and a study of the variations 

 represented by the several fractions seems to indicate fortuity rather 

 than system. Eemmler regards his results as indicating lack of hoino- 

 geneity in his material; but it seems more probable that such differences 

 as exist are due to experimental errors and to impurities acquired in the 

 long process of purification to which each fraction was submitter!, rather 

 than to any uncertainty regarding the nature of cobalt itself. 



^ Zeit. anorg. Chem., 2, 221. Also more fully in an Inaugural Dissertation, Erlangcn, 1S91. 



