238 MORRIS LOEB 



the chance errors of observation become proportionately very 

 great. Hence I agree with Raoult when he says that the 

 method of determining molecular weights by the depression 

 of the freezing-point is preferable to the method by vapor 

 tensions. But for the problem which immediately interested 

 me I lacked a liquid which would solidify, and also dissolve 

 iodine with a pure violet color, benzene, for instance, giving 

 a very [812] impure bluish-brown. Nevertheless I endea- 

 vored to obtain what corroborative evidence I could by experi- 

 menting on the freezing points of iodine in acetic acid and in 

 benzene, but was forced to give up the attempt by the very 

 slight solubility of iodine in these menstrua at low tempera- 

 tures; the molecular weight of iodine as calculated from vari- 

 ous series of observations seemed to increase continuously 

 with the concentration, so that there was no point in the nar- 

 row limits between extreme dilution and saturation at which 

 the molecular weight would appear constant, and could be 

 accepted as trustworthy. A paper published since then by 

 Paterno and Nasini 1 on this subject contains a few figures 

 for the molecular weight of iodine in acetic acid and benzene 

 solutions, but I am unable to draw any other inference from 

 them than from my own. 



1 Berichte, 21, 2155 (1888). 



