CONTRIBUTIONS FROM THE CHEMICAL LABORATORY OF 

 HARVARD COLLEGE. 



A REVISION OF THE ATOMIC WEIGHT OF NICKEL. 



FIRST PAPER. — THE ANALYSIS OF NICKELOUS BROMIDE. 

 By Theodore William Richards and Allerton Seward Cushman. 



Presented June 9, 1897. 



Introduction. 



Of the atomic weights to-day those of nickel and cobalt are among the 

 most interesting, not only because the two values are so close together, 

 but also because the purely elementary character of these metals has 

 been recently doubted.* A careful study of the available literature upon 

 the subject leaves the impartial critic in grave doubt as to the true 

 values to be accepted, hence an experimental revision seems to be im- 

 perative ; and the present work is a part of a comprehensive attempt to 

 conduct such a revision. The very useful and complete index of the 

 work which has been done upon this subject, recently published by Pro- 

 fessor Clarke,t makes a detailed statement of the various researches un- 

 necessary here ; but a chronological list is appended. 



The Atomic Weight of Nickel. 

 = 16. 

 1826. By Analysis of Chloride. 



Rothoff 59.1 



1852. Reduction of the Oxide by Hydrogen. 



Erdman and Marchand 58.2-58.6 



1856. Conversion of Nickel to Sulphate. 



Deville 58.85 



1857. Analysis of the Oxalate. 



Schneider . 58.07 



1858. Analysis of the Sulphate and Chloride. 



Marignac 58.4-59.29 



* Zeit. Anorg. Chem., II. 235; Bericlite d. d. ch. Gesell., 1889, pp. 11, 2026. 

 t Recalculation of the Atomic Weights, Smithsoii. Misc. Coll., Constants of 

 Nature, Part V., 1897, p. 291. 



VOL. XXXIII. — 7 



