40 
DR. W. A. BONE AND MR. R. V. WHEELER ON THE COMBINATION OF 
The Absorption of Hydrogen by Silver.—At Dull Red Heat. 
It now became necessary to obtain some further evidence concerning the absorption 
of hydrogen by silver at high temperatures. Accordingly the combustion tube 
(capacity = 135 cub. centims.) containing the 62 grammes of silver gauze employed 
in the preceding experiments was transferred to the “ absorption” apparatus, where 
it was thoroughly exhausted at dull red heat (circa 650°) during several hours. 
Pure hydrogen was then admitted up to a pressure of 744 millims. A rapid 
absorption of the gas at once began, the pressure falling to 381 millims. in 25 minutes, 
as follows :— 
t . . 
0 
2 
4 
6 
8 
10 
15 
20 
25 minutes 
p 
774 
689 
610 
547 
499 
464 
414 
395 
381 millims. 
The tube was next allowed to cool, and was subsequently exhausted at the room 
temperature until the whole of the unabsorbed gas (about 25 cub. centims.) had been 
extracted. The temperature was thereupon again raised to dull red heat, and the 
exhaustion continued for 15 hours longer. During the whole of this time hydrogen 
was very slowly evolved (about 7 ‘5 cub. centims. were collected within the first three 
hours), and a mirror of silver appeared near the cool end of the combustion tube, a 
circumstance which suggested the decomposition of a hydride rather than the mere 
giving off of “ condensed” or “ occluded ” gas- 
in order to completely “ dehydrogenise ” the surface, pure oxygen was now 
admitted to the red hot tube up to a pressure of 763 millims. During the next 
minute the pressure rapidly fell to 683 millims., and water condensed in the cool ends 
of the tube. There then followed a very slow fall in pressure (29 millims. during the 
next 14 minutes), probably due to a small absorption of oxygen. The pressure 
records during this treatment with oxygen were as follows :— 
t . . . 
0 
1 
2 
3 
4 
5 
10 
15 minutes 
P . . . 
763 
686 
680 
675-5 
672 
669 
662-5 
657 millims. 
IDO formed 
The tube was next continuously exhausted at dull red heat for 14 hours, after 
which pure hydrogen was once more admitted up to a pressure of 747 millims. 
There followed a very rapid absorption, the pressure falling to 432 millims. within the 
first five minutes, and to 180 millims. by the end of an hour. During the first 
minute there was a slight condensation of moisture in the cool ends of the tube, due 
