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PROCEEDINGS OF THE AMERICAN ACADEMY. 



questions experimentally would be far from uninteresting, but it is suffi- 

 cient for the present purpose to prove in the manner described above that 

 nickel treated as we have treated it in the following determinations does 

 not occlude an important amount of hydrogen, and does not oxidize in 

 dry air. Confirmatory evidence will be found in the paper upon cobalt 

 which follows. 



Fig. 2. Apparatus for Redccing the Bromide. 



Before it was possible to use the data thus obtained for the calculation 

 of the desired atomic mass, the weight of sodic bromide existing as impu- 

 rity within the spongy metal must obviously be found. Accordingly the 

 residue was digested with successive portions of pure water in a platinum 

 dish, and the bromine in the filtrates was precipitated and weighed as 



