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DBS. L. MONT), W. RAMSAY, AND J. SHIELDS, ON THE 



heat, or (3) the presence of a film of oxide on the foil. Of these (2) is unlikely, so 

 that the deficit may be regarded as due to (1) and (3), and probably chiefly to (3). 



After all the hydrogen had been extracted from the foil, it was again charged with 

 hydrogen. A slow absorption went on, and this was promoted at the beginning by 

 warming. On opening the tube and bringing the foil, partially charged with hydrogen, 

 into contact with the air, it became distinctly warm to the touch, and after standing 

 i'or a short time drops of water were deposited on the walls of the tube. 



Under proper conditions, therefore, as above set forth, a sample of new palladium 

 foil which initially would only occlude a few volumes of hydrogen may be made to 

 occlude 846, or roughly 850, volumes, that is approximately the same quantity of 

 hydrogen as palladium black or sponge. 



New palladium foil, or even fused palladium, if left for a sufficiently long time 

 (possibly mouths or years) in an atmosphere of hydrogen at the ordinary temperature, 

 would probably absorb the full quantity of hydrogen, the effect of gentle warming 

 being to accelerate (as above) the diffusion of the hydrogen from the fully charged 

 outer skin of the metal towards the centre. 



A few additional experiments on the behaviour of palladium to other gases may 

 conveniently be recorded here. Some palladium black was fully charged with 

 hydrogen, and from this as much hydrogen as possible was extracted at 100. On 

 now admitting sulphur dioxide only about 90 volumes were taken up, in place of about 

 800 volumes of hydrogen removed. Palladium sponge when treated with sulphur 

 dioxide absorbed only two volumes. About seventeen volumes of carbon monoxide 

 were occluded by palladium sponge. 



Palladium black and sponge, like platinum sponge, cause a jet of hydrogen to ignite. 

 When hydrogen was led over palladium black which had absorbed more oxygen at a 

 high temperature, it glowed brightly. A specimen of ordinary palladium black, 

 however, did not glow on passing hydrogen over it, although it became very hot. 

 Apparently it was not itself sufficiently rich in oxygen. Palladium black or sponge 

 charged with hydrogen glows like pyrophoric iron on being shaken out into the air. 



