246 Mr. J. J. Thomson on the 



so that for the compound of oxide of methyl and hydrochloric 

 acid at the pressure of one atmosphere the free time is about 

 6*14 times the paired time. 



We will now go on to consider the effects of either the 

 methyl oxide or the hydrochloric acid being in excess. To do 

 this we must use equation (6), viz. 



(M.-p)(R-p)=j P . 



We can calculate the quantity r/t if we know the quantity of 

 the compound formed when equal quantities of oxide of 

 methyl and hydrochloric acid are present, i. e. when M = N. 

 We can then, by the use of this equation, determine the 

 quantity which ought to be formed when the methyl oxide and 

 the hydrochloric acid are mixed in any other proportion. In 

 the experiments we shall compare with the results obtained by 

 this equation the methyl oxide was in excess. We shall 

 measure this excess, which we shall call e> by the rate of the 

 difference between the number of free methyl oxide and 

 hydrochloric molecules to the number of hydrochloric mole- 

 cules in the vessel, so that 



n = m-\-eM.. 



Equation (6) then becomes 



n (m + eM)=y|M-ffl} ; 

 or, if m/M=#, 



where c=rt/M. We determine c by making the formula 

 true when e = 0. 



Dissociation of the Compound of Methyl Oxide and Hydro- 

 chloric Acid. 



e. 



f 



— >» 





Calculated. 



Observed 







. . -884 



•884 



•222 



. . -846 



•838 



•5 



. . -822 



•833 



1-333 



. . -784 



•761 



3-0 



. . -764 



•661 



The agreement of these, with the exception of the last, 

 is as close as could be expected; the last discrepancy, how- 

 ever, seems to show that some circumstances which we have 

 neglected have to be considered, and the most likely one 

 seems to be the effect of the collisions. If this were so, we 



