OCCLUSION OF HYDROGEN AND OXYGEN BY PALLADIUM. 



109 



metal, it is to be inferred that palladium black will behave in the same way, although 

 perhaps to a greater extent. 



In the first experiment 3 '5 19 grams of palladium black were heated in an atmos- 

 phere of oxygen in an apparatus similar to that employed for the corresponding 

 experiments with platinum. The following results show that oxygen was steadily 

 absorbed : 



Heated for 



2 hours at 132" 

 6 184 

 6 237 

 6 280 



Total . 



101-38 



345-9 



Up to 280 C. the total quantity of oxygen absorbed, viz., 101 '38 cub. centims. 

 = 0'1450 gram, is more than half the quantity of oxygen (0'2656 gram) necessary 

 to form the compound Pd 2 0. Owing to an accident, which prevented the experi- 

 ment being carried further, a new portion of palladium black was taken, and the 

 heating in oxygen started at 280 C. The following results were obtained : 



OXYGEN Absorbed by Palladium at High Temperatures. 



Palladium black used, 2'8100 grains = O234 cub. centim. 



The quantity of oxygen theoretically necessary for the formation of the oxide Pd.jO 

 is 0-2121 gram, and it will be observed that the oxygen actually absorbed exceeds 

 this quantity. There is no reason to suppose that the absorption of oxygen had 

 ceased after the experimental tube had been heated for three hours in the naked flame. 

 The experiment was stopped at this stage, however, in order to see whether the 



