RICHARDS AND CDSHMAN. — ATOMIC WEIGHT OF NICKEL. 339 



consisted chiefly of nickelous hydrate, two more determiuations were 

 made with new material. Since enough data for the atomic weight had 

 been obtained, and time pressed, the bromide of nickel was not weighed 

 in the first place. In these analyses the nickel dissolved as hydroxide 

 was also weighed. 



Besides this quantitative proof that the residue consisted of nothing 

 but sodic bromide and nickelous hydrate, many qualitative analyses had 

 shown the absence of lime, alumina, silica, and even potash, from the so- 

 lution poured off from the reduced nickel. Traces of sulphuric acid 

 were found, as has been said, only in the first specimens. 



In the light of all these results, no doubt seemed to remain as to the 

 proper mode of correcting the direct gravimetric results of the reduction. 

 Obviously the weight of the sodic bromide must be subtracted from the 

 weights of both the nickelous bromide and the metal formed from it by 

 the action of the hydrogen ; for the salt existed in each. On the other 

 hand, the nickelous hydroxide was simply to be neglected ; for this sub- 

 stance was formed after the last weighing had been finished. The tem- 

 perature used for the reduction was so low that no sodic bromide was 

 vaporized ; at least none could be found in the cooler parts of the 

 reduction tube. 



Analyses 5 and 6 were made with nickelous bromide of the grade of 

 purity represented by the numeral II. in the former paper, while all the 

 others were made with that labelled III., which had been made through 

 the carbonic oxide process. The headings of the various columns will 

 show with sufficient clearness the meanings of the figures given below. 



In this series of results, the lowest is 58.696, while the highest is 

 58.719, a variation ±0.012 from the mean. Adding all the determina- 

 tions together, 24.31725 grams of nickelous bromide yielded 6.52286 

 grams of pure washed nickel and 0.02778 gram of sodic bromide, calcu- 

 lated from 0.0507 gram of argentic bromide. These two weights, taken 

 in connection with the amount of bromine found a year ago, furnish a 



