OCCLUSION OF OXYGEN AND HYDROGEN BY PLATINUM BLACK. 
14L 
in the following section the result of admitting the theoretical quantity of a I’educing 
agent, viz., hydrogen, is described. 
IV. On the Existence of Platinum Oxygen and Platinum Hydrogen in presence 
of each other. 
All previous attempts to prepare a specimen of platinum black which would 
occlude oxygen directly having failed, the following experiments were made in the 
hope of obtaining the substance we were in search of. The amount of oxygen 
contained in a certain sample of platinum black was determined by a direct experi¬ 
ment ; and it was found that 5-815 grams gave, on exhaustion in vacuo at a red heat, 
25-56 cub. centims. = 92-6 volumes of oxygen. By taking another weighed quantity 
of the same sample and charging it -with rather less than rlie amount of hydrogen 
theoretically necessary for converting all the oxygen into water, it was expected that 
the platinum black Avould then be in a position (after pumping off the water formed 
at the ordinary temperature) to absorb oxygen directly in the calorimeter. For this 
Fig. 3. 
purpose 5 051 grams of platinum black were placed in the experimental tube. A, 
(fig. 3) which was then exhausted. It was estimated that this quantity of platinum 
black contained 22-20 cub. centims. of oxygen, for the complete conversion of which 
into water 44-4 cub. centims. of hydrogen would be necessary. 
As a matter of fact, only 39-05 cub. centims. of hydrogen were admitted from the 
gas burette, B. The apparatus was then allowed to stand for a few hours, when the 
tap, C, communicating- with the pump was opened. Practically all the liydrogen 
admitted was found to be absorbed, for on putting the pump in action only about 
a quarter of a cub. centim. of gas was extracted. On surrounding the experimental 
tube. A, with a copper sheath and applying- a Bunsen burner, 10-75 cub. centims. 
of gas were pumped off, which on examination was found to consist of :— 
