﻿of Phosphorus, Sulphur, and Aldehyde. 515 



Table II. — Phosphorus and Oxygen (continued). 





Temperature = 



30°-18 to 30°-31. 



Pressure of 



aqueous vapour 



= 288*9 mm. bromnaphth. 



)i 



phosphorus- vapour =2*36 mm 



» 



V 



nitrogen . 



= 260*7 mm. „ 







P 



P 





t. 





in milliins. of 

 bt onmaphthalene. 



in millims. of 

 mercury. 



K. 









1334-5 



87-2 





4 





12400 



76-7 



175 



6 





1197 



70-9 



17-2 



9 





11260 



640 



179 



11 





1081-0 



59-0 



18-0 



13 





1037-0 



54-2 



18-3 



17 





958-0 



45-4 



183 



21 





883-0 



370 



18-6 



28-5 





774-5 



25-0 



18-5 



32-5 





750-5 



22-3 



174 



37-5 





7210 



19'0 



164 



58-5 





6550 



11-7 



139 



105'5 





559-0 



1-0 



12-9 



Determinations of the limiting pressure, above which no 

 reaction takes place, were only made at 20°. In one experi- 

 ment at 20 o, 2 (see Table II.) the reaction just began when 

 the pressure of the oxygen was 696 millim. In another at 

 20 o, 5 it began at 671 millim., but not at 723 millim. We 

 may therefore say that at a temperature of 20°-21° phos- 

 phorus will just begin to oxidize in wet oxygen when its 

 pressure is about 700 millim. 



Joubert* gives two series of experiments on the pressure 

 at which phosphorus just begins to be luminous in oxygen. 

 At 20 O- 2, one series gave 787 millim., the other Q6Q millim. 

 The pressure at which oxidation just begins appears, there- 

 fore, to be identical with that at which the phosphorescence 

 just becomes visible. 



The curves in fig. 2 show the connexion between the pres- 

 sure and the velocity of the reaction between phosphorus and 

 wet oxygen. The experiments at 20° being the most com- 

 plete have been used in drawing them. The values of the 

 velocities of reaction have been obtained by dividing the 

 successive decrements of the pressure by the corresponding 

 increments of the time. 



These values of -ry are taken as ordinates, and the mean 

 * Loc. cit. 



