114 Potts — RowlanaVs New Method. 



chief advantage lies in the fact that a very small quantity of 

 the material is necessary. In the experiment only 360 grams 

 were used. Much less than this amount could be used, with 

 nearly as great accuracy as in the case given. For the value 

 of the resistance H could be increased by decreasing the period 

 of the current used. 



In conclusion I wish to express my sincere appreciation of 

 much assistance received from Professors Rowland and Ames 

 during three years spent in study at the Johns Hopkins Uni- 

 versity. The investigation was suggested by Professor Row- 

 land, and the methods used were those devised by him and 

 described in the articles noted above. 



Johns Hopkins University, 

 May 1, 1900. 



