﻿524 Dr. T. Ewan on the Rate of Oxidation 



The part of the apparatus to the left of D having been filled 

 with oxygen at a somewhat greater pressure than exists in F, 

 the tap E is opened for a moment to equalize the pressure on 

 both sides of D, and the position of the mercury in A read 

 off. By raising B the pressure of the oxygen can always be 

 kept equal to the constant pressure in F. The diminution of 

 volume per minute, when reduced to standard pressure, is 

 then proportional to the velocity of the reaction. When the 

 velocity has become constant, the pressure in F is reduced, 

 the tap E opened to equalize the pressure again, and further 

 readings made at the new pressure. 



The following Table contains the numbers obtained by this 

 method. 



In it — is the diminution of the volume per minute, the 



volume being measured at pressure P. 



j- is the rate of change of the volume, calculated for a 



pressure of 819*7 millim., and it is proportional to the quantity 

 of oxygen which is converted into sulphur dioxide per 

 minute, that is to the rate of the reaction. 





Table V. — Sulphur and Oxygen. 





Pressure. 

 P. 



Av 

 ~L1' 



dv 

 . dt' 



Tempera- 

 ture. 



K 2 . 



k. 



809-8 



•0176 



•0174 



158 



•0985 



0035 



587-0 



•0244 



•0175 



158 



•0841 



•0035 



380-6 



•0459 



•0213 



158 



•0820 



•0042 



198-5 



•147 



•0356 



159 



0975 



•0069 



105-6 



•456 



•0588 



159 



•118 



•0156 



43-8 



1-77 



•0946 



159 



•108 



•0163 



819-7 



•0149 



•0149 



158 



•085 



•0030 



578-7 



•0243 



•0172 



159 



•082 



•0034 



422-2 



•0349 



•0180 



159 



•088 



•0043 



306-0 



•0653 



•0244 



159-5 



•084 



•0048 



194-0 



•133 



•0315 



159-2 



•085 



•0061 



147-3 



•222 



•0399 



n 



•093 



•0077 



95-9 



•455 



•0532 



159-4 



•098 



•0100 



41-8 



1-84 



•0938 



>y 



•104 



•0161 



The constant K 2 is calculated from the following equation, 

 which is essentially identical with equation 3 : — 



dv rr t»i i JP 



dt 



P- 



p 



