490 Dr. Harry C. Jones on the 



very closely with that of cane-sugar for the most dilute 

 solutions. The minimum value here also is very nearly 

 reached at Oln, but for dextrose is slightly lower than for 

 cane-sugar. As the concentration increases from about 0*1 n 

 the molecular lowering of dextrose increases, but the change 

 is much less rapid than for cane-sugar. In general tne same 

 qualitative changes in the molecular lowering with changes 

 in the concentration of the solution are observed with dex- 

 trose as with cane-sugar, and for the more dilute solutions 

 the results from the two compounds agree very well with each 

 other. 



Urea* — Urea shows the same variations in molecular 

 lowering with concentration as the other compounds for the 

 more dilute solutions. This value is somewhat less for urea 

 for the same concentrations. The molecular lowering of this 

 compound becomes constant at about 0*1 n, and remains un- 

 changed as the concentration is increased, at least as far as 

 my experiments were carried. There exists, then, this marked 

 difference between the more concentrated solutions nf urea 

 and of the two carbohydrates which have been considered. 



Since the molecular lowering of urea reaches a constant, 

 this can be taken as the constant for water. This value deter- 

 mined experimentally can then be compared with that calcu- 

 lated by van't Hoff. 



Phenol. — Here also the same general results are obtained 

 from the more dilute solutions, but the molecular lowering 

 does not reach a minimum for the most concentrated solutions 

 used. This decreases below the calculated constant for water, 

 being only about 1*714 at 0*619 w. That phenol may possibly 

 undergo a very slight electrolytic dissociation has been shown 

 by Bader *. 



Ethyl and Propyl Alcohol. — Eesults of the same general 

 character as above considered were found for the more dilute 

 solutions of both alcohols. The molecular lowering of ethyl 

 alcohol for the same concentrations is considerably greater 

 than that of propyl, and agrees fairly well with that of dextrose 

 and cane-sugar. The molecular lowering of both alcohols be- 

 comes practically constant at a concentration slightly greater 

 than O'ln. 



All the organic compounds thus far examined show, then, 

 this increase in the molecular lowering with increase in 

 dilution. Since compounds have been selected which differ 

 chemically so widely from one another, this can scarcely 

 depend on chemical composition or constitution, but seems 

 to be more or less general. Investigations have not as yet 



* Bader, Zeits. pliys. Chem. ri. p. 291. 



