248 PROCEEDINGS OF THE AMERICAN ACADEMY 



compound being taken as 100 in each experiment, aud the amounts 

 from the meta and ortho compounds given in percentages of this. 

 Either two or four grammes of substance were taken in each experi- 

 ment. 



Table III. 



These numbers, entitled to very little consideration as independent 

 experiments, confirm the preceding results from the meta compound, 

 even more closely than could be expected when the large limit of 

 error is remembered ; and further would seem to indicate that the 

 rate for the ortho compound is about one half that for the para, if it is 

 assumed, as before, that the relative rate does not vary with the 

 length of time during which the reaction has run ; a result confirmed 

 by the experiment made first in the preceding series, and therefore 

 entitled to the most weight, which gave 55 %. 



Berthelot and Pean de St. Gilles,* in their classic researches on 

 etherification, found that after a certain time the water set free in the 

 reaction prevented further formation of the ether ; in other words, 

 that there was a limit to etherification. Although it did not seem 

 probable that there would be such a limit to this reaction, some experi- 

 ments were tried to test the question, with the following results : — 



I. Time somewhat more than two hours : — 



1 grm. of parabrombenzylbromide lost 0.3203 grm. of bromine. 

 1 grm. of metabrombenzylbromide lost 0.2701 grm. of bromine. 

 0.8200 grm. of parachlorbenzylbromide lost 0.3082 grm. of bromine. 



To this may be added the following, in which the method was 

 somewhat different ; in II. common alcohol being used, and in III. 

 the reaction taking place in a sealed tube, with dilute alcohol as the 

 solvent. 



II. Two portions of parabrombenzylbromide, 1 grm. each, lost in 

 twenty-five minutes 0.3113 grm. and 0.3074 grm. of bromine. 



III. In thirty minutes 0.3046 grm. and 0.3093 grm. of bromine. 



* Ann. Chim. Phys., 3d ser., Ixviii. p. 225. 



