Pressures of Saturation of Oxygen. 459 



is to be ascribed to the influence of the hydrogen, which is 

 passed through the liquid oxygen in a slow current ; when 

 we employ such low pressures the boiling must be facili- 

 tated by this means. 



Second Series. 



No. 



Pressure. 



Temperature. 



No. 



Pressure. 



Temperature. 



o 





millim. 







raillim. 



1 



731-1 



-182-2 



8 ... 



541 



-201-6 



2 



629-1 



-183-3 



9 ... 



375 



-204-9 



3 



479 1 



-185-8 



10 ... 



33-5 



-205-2 



4 



279-1 



-190-5 



11 ... 



160 



-208-8 



5 



1791 



-194 



12 ... 



16-0 



-209-3 



6 



129-1 



-196-25 



13 ... 



15-0 



-209-7 



7 



79-1 



-199-5 



14 ... 



130 



-210-2 



Third Series. 



No. 



Pressure. 



Temperature. 



No. 



Pressure. 



Temperature. 





millim. 







millim. 





1 ... 



743-8 



-182-56* 



12 ... 



11-5 



-2095 



2 ... 



141-8 



-195-9 



13 ... 



11-0 



-2097 



3 ... 



91-8 



-198-7 



14 ... 



10-5 



-209-8 



4 ... 



61-8 



-201-1 



15 ... 



9-5 



-2102 



5 ... 



41-8 



-203-4 



16 ... 



90 



-210-4 



6 ... 



31-8 



-204-8 



17 ... 



8-75 



-2106 



7 ... 



21-8 



-206-8 



18 ... 



8-5 



-210-8 



8 ... 



14-5 



-208-6 



19 ... 



8-0 



-2111 



9 ... 



13-0 



-208-9 



20 ... 



7-75 



-211-2 



10 ... 



12-5 



-209-2 



21 ... 



7-5 



-211-2 



11 ... 



120 



-209-3 





. 





* This is the mean of 22 determinations. 



All the temperatures have been calculated to two decimal 

 places ; the second decimal served only for correction. 



Having thus determined the pressures of saturation for 

 oxygen, I wished to ascertain if the rule of van der Waals * 

 applied to this body. This law says : — " If the absolute 

 temperatures of various substances are proportional to their 

 absolute critical temperatures, their vapour-pressures will be 

 proportional to their critical pressures. " This statement has 

 been tried for different substances, but iC has not been proved 

 by experiment to be true, except in a very limited number of 

 cases" f. I therefore divided my numbers by the critical 

 constants, and compared the results with the numbers for 

 several other bodies, drawing by means of these numbers the 



* Van der Waals, Continuitdt, transl. by Roth, 1881, p. 128. 



t Young, 'On the Generalizations ' Phil. Mag. [5] xxxiii. p. 173, 



1892. 



