702 Research Staff of* the Gr. E. C, London, on the 



(d) If not pure hydrogen, but hydrogen mixed with CO,, 

 is admitted, the amount of hydrogen that can be absorbed is 

 almost or quite independent of the amount of CO that is 

 absorbed at the same time. Thus, in one experiment, the 

 limit for pure hydrogen was 0*042 mm.; i£ 04 mm. of 

 hydrogen together with 0*06 mm. of CO, making a total 

 pressure of 0'10, all this mixture was absorbed. This 

 appears to be the strongest proof that the action is not 

 chemical, at least in the case of CO. 



On the other hand, direct experiments showed that the 

 amount of hydrogen that can be absorbed in the discharge 

 does increase in some measure and in some conditions with 

 the amount of phosphorus vapour mixed with it. It was 

 difficult to obtain quantitative results, but such measure- 

 ments as could be made did not indicate proportionality 

 between phosphorus added and hydrogen absorbed. Some 

 of these observations are noted below. 



25. The influence of the walls of the vessel. — These experi- 

 ments prove conclusively that the disappearance of the gas 

 is not due simply to chemical combination with the phos- 

 phorus. The next experiments show that the state of the 

 walls of the vessel influences profoundly the disappearance of 

 the gas. 



(a) The most striking experiment was made for the first 

 time by accident. If the lamp is filled with phosphorus 

 vapour, and then air admitted, the phosphorus is oxidized 

 and deposited on the walls, and alters somewhat their lustre. 

 If the lamp is now exhausted, and either hydrogen or CO 

 admitted (the other gases were not investigated), then none 

 of the gas can be made to disappear by the discharge, 

 whether or no phosphorus is present. If phosphorus is 

 present, it is deposited on the walls as usual as a yellow film, 

 but no gas disappears. The film of phosphorus oxides on 

 the walls entirely prevents the absorption of gas. 



(b) Other experiments directed to changing the state of 

 the walls so that the amount of gas absorbed should be 

 altered were not definitely successful, although indications 

 which it is hoped to discuss in a later communication 

 have been obtained. But it could be p-oved that this 

 state affected the condition of the gas after disappearance. 

 For this purpose hydrogen was introduced into the lamp at 

 various pressures, and the discharge passed with the tap A 

 open, so that an unlimited supply of phosphorus vapour was 

 available. In those circumstances any quantity could be 

 made to disappear. The lamp was now baked in conditions 

 known to liberate in a few minutes all the gas that could be 



