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maximum active deposit on the positive terminal was not obtained until 

 the pressure was 14 mms. The maximum active deposit on the cathode 

 was about 2.68 times the maximum deposit on the anode, and this, it 

 will be seen, is not very different from the ratio which was found for the 

 maximum activities obtained in the case of air. Care was taken in the 

 experiments with carbon dioxide and air to repeat all the observations 

 a nimiber of times, and the curves indicated m Figs. YII and XII were 

 uniformly obtained for the two gases under the conditions described. 



TABLE V 



VII. Activity of Deposits Obtained in Hydrogen at Different 



Pressures. 



Another series of measurements was made with hydrogen, under 

 conditions similar to those already described with air and carbon dioxide, 

 and the active deposits obtained at the various pressures are given in 

 Table V, and a curve representing them in Fig. XIII. From these ob- 

 servations it will be seen again, that as the pressure was lowered, the 

 active deposits on both electrodes steadily increased, passed through 

 majximtmi values, then decreased, and on the decrease approached 

 equality at the lowest pressures examined. In hydrogen the maximum 

 active deposit on the cathode was obtained at about 350 mms., but the 

 maximum active deposit on the anode was not obtained until about 80 

 mms. pressure was reached. The maximum active deposit on the nega- 

 tive electrode was about 3.3 times the maximum active deposit on the 

 positive terminal. Eepeated measurements have not been made to con- 

 firm these results, but the same precautions were taken with hydrogen 

 as with air and carbon dioxide. It will be seen from the values given, 

 that the ratio of the maximum activities for the two terminals in the 

 case of hydrogen is only slightly less than corresponding ratios for air 

 and carbon dioxide. 



