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PROCEEDINGS OF THE AMERICAN ACADEMY 



VI. and VII. Only one experiment was made with baric sulphate, 

 but the result is appended for the sake of completeness. From No. 

 10 it is seen that 100.000 parts of crystallized cupric sulphate are 

 equivalent to 93.289 parts of baric sulphate. But the same amount of 

 the same specimen of the salt had been shown to contain 25.448 parts 

 of copper and 36.109 parts of water. (See pages 260 and 267.) 

 From these data : — 



VI. BaS04 : Cu = 93.289 : 25.448 = 233.16 : 63.603 

 VII. BaS04 : CuSOi = 93.289 : 63.891 = 233.16 : 159.685 



From the last value Cu = 63.625. The atomic weight of barium 

 probably lies between 137.0 and 137.2; the mean value is assumed 

 above. The corresponding variations of the atomic weight of copper 

 would be from 63.57 to 63.63 with the first ratio, and from 63.54 to 

 63.69 with the second. 



The results of the seven ratios dependent upon the analysis of 

 cupric sulphate are collected in the following table. 



The Atomic Weight op Copper. 



The correction of the experimental mean, in each case, for the 

 amount of copper and sulphuric acid lost during electrolysis, dimin- 

 ishes the variations noticeable above to a remarkable degree. But 

 since the validity of this correction is doubtful, and since its applica- 



