204 PROCEEDINGS OF THE AMERICAN ACADEMY 



sumed in its preparation ; and it did not seem worth while to sacrifice 

 the large amount of time necessary to prepare so much paraiodbenzyl- 

 bromide, especially as its decompositions seemed analogous to those of 

 the more accessible p'arabrombenzylacetate, which will be studied in this 

 laboratory. The following account of the attempts to prepare it is, 

 however, given, as it throws some light upon the nature of the sub- 

 stance. The first difficulty encountered was due to the fact that the 

 sodic acetate unly partially decomposed paraiodbenzylbromide. The 

 two substances were boiled with absolute alcohol, and an oily product 

 obtained, which solidified at 0°, and after crystallization from alcohol 

 melted at 45*^ : the results of an analysis of this substance are given 

 under I. ; it was then heated once more with sodic acetate and abso- 

 lute alcohol, and the result analyzed, when the numbers given under 

 IT. were obtained. 



I. 0.4007 grs. substance gave 0.4416 gr. CO2 and 0.0909 gr. H2O. 



II. 0.2936 gr. substance gave 0.3403 gr. CO^ and 0.0738 gr. H^O. 



Found. 

 Calculated CTHelCaHsO^. I. II. Calculated C-HelBr 



Carbon 39.12 30.05 31.61 28.28 



Hydrogen 3.26 2.52 2.79 2.03 



These numbers seem to show that the substance was nothing more 

 than a mixture of the acetate and bromide, and this conclusion is 

 strengthened by the fact that it attacked the eyes like the bromide. 

 In order to obtain the acetate from this mixture, it would have been 

 necessary to use fractional distillation, which had been found, in the 

 case of parabrombenzylacetate, to cause almost complete decomposi- 

 tion : it was therefore thought better to try to decompose the paraiod- 

 benzylbromide completely by using ■argentic, instead of sodic, acetate. 

 In this case, the product was an oil, which showed no signs of solidifi- 

 cation, even after standing in an open watch-glass for some time. The 

 term then came to an end, and it remained exposed to the air during 

 the summer vacation of three months, at the end of which time the 

 watch-glass contained a solid residue, proved to be paraiodbenzoic acid 

 by its melting-point and the following analysis of its silver salt: — 



0.2185 gr. substance gave by precipitation with hydrochloric acid 

 0.0857 gr. AgCl. 



Calculated for CgHJCOaAg. Found. 



Silver 30.42 " 29.62 



