928 Research Staff of the G. E. C, London, on the 



Ihe Rate of Absorption with Phosphorus. 



13. Just as there is a very rapid absorption of gas at the 

 moment when salt is evaporated from the filament in the 

 absence of phosphorus, so there is a very rapid absorption 

 when phosphorus is evaporated from the filament in the 

 absence of salt, or at the moment when phosphorus, present 

 originally as vapour, is deposited on the walls as red phos- 

 phorus by the starting of the discharge. Accordingly, even 

 when phosphorus is used without salt, the absorption takes 

 place in two stages, unless the phosphorus is first deposited 

 on the walls as described in Par. 7 ; the first stage is practi- 

 cally instantaneous and is impossible to control ; the second 

 is very much slower. The ratio between the amounts 

 absorbed in the two stages differs, as might be expected, with 

 the initial pressure ; as this pressure is increased, the amount 

 absorbed in the first rapid stage is increased relatively to 

 that absorbed in the second slow stage. But, as noted 

 previously, the sum of the two amounts is approximately 

 independent of that pressure. 



Attempts have been made to relate the rate of absorp- 

 tion to the ionization in a manner similar to that adopted 

 in (III.), but they have met with no success. Indeed, the 

 experiments of (III.) indicate that, even if the experimental 

 difficulties could be overcome, the interpretation of the 

 measurements would be very complex. For it was shown 

 there that, in order to obtain any simple relation between 

 ionization and absorption, it was necessary to suppress, as 

 far as possible, recombination and the arrival of positive ions 

 at the cathode. During the very intense ionization that 

 accompanies the first stage of the absorption, recombination 

 is unavoidable ; in the second, either the ionization is very 

 much greater than that found permissible in (III.), or the 

 absorption is so slow that the disturbing factor mentioned in 

 Par. 5 enters. Moreover, the theory of the action that has 

 been proposed, and is confirmed by the experiments of this 

 paper, indicates that the action which produces absorption 

 takes place, not in the gas as in (III.), nor even at the 

 metallic electrodes, but at the glass walls which are acting 

 as electrodes of both signs. In such conditions the difficulties 

 of interpretation would be enormously increased. 



All that has been achieved is a demonstration that, in any 

 particular conditions of pressure and state of walls, the rate 

 of absorption is approximately proportional to the ionization. 

 But the only conclusion which it seems permissible to draw 

 from that fact is that absorption is not an action requiring 

 the meeting of two or more charged particles. 



