﻿522 



Dr. T. Ewan on the Rate of Oxidation 



to a temperature of about 160° in the vapour of boiling tur- 

 pentine. The following Table contains the results of an 

 experiment made by this method. 



Table IV. — Sulphur and Oxygen. 



Temperature = 156°. 

 Vapour-pressure of sulphur = 11*5 millim.* 

 Pressure of nitrogen . . =8*1 millim. 



Time in minutes 

 from beginning. 



Total pressure. 



Partial pressure 

 of Oxygen 



K v 



t. 





=p. 









1325 



114-0 





18 



121-0 



102-5 



74 



41 



107-2 



88-7 



64 



58 



93-4 



74-9 



65 



75 



79-9 



61-4 



63 



84 



71-6 



53-1 



65 



97 



58 7 



40-2 



65 



107 



47-6 



291 



65 



119 



30-0 



11-5 



65 



128 



20-0 



1-5 



63 



K x was calculated from the equation obtained by the inte- 

 gration of equation 3. Owing to the magnitude of p 1 , 

 equation (3 a) is insufficiently accurate, and two further 

 terms of the expansion of the logarithm have to be included. 

 The equation thus obtained is : — 



-Kxt=|,(P-a)'i+( 



2a , f 

 tf 24 aP 



)(P-a)* 



6 V« 



=-tan 



24 ^ 

 -f const. 





!>(3 



The integration-constant is determined as before. With 

 the exception of the first number, the values of K x are very 

 satisfactorily constant ; equation (3) therefore applies also to 

 this reaction. 



* On further heating pressure remained constant at 18-5 millim. ; after 

 cooling pressure = 5-4 millim. at 12°. From which pressure of the sul- 

 phur-vapour = 10-4 millim. Another experiment gave 12-6 millim. 



