25O REPORTS ON INVESTIGATIONS AND PROJECTS. 



We have studied the hydrolysis and the dehydrolysis time factors, and 

 some interesting facts have been established. The dissociations of these 

 substances, and the temperature coefficients of conductivity both in conduc- 

 tivity units and in per cent have been worked out. The results of these in- 

 vestigations with the inorganic salts are also incorporated in the monograph 

 just referred to. (Publication No. 170.) 



This work will be extended next year to a much larger number of salts 

 and organic acids. 



Morse, H. N., Johns Hopkins University, Baltimore, Maryland. Grant No. 

 764, allotted December 15, 191 1. Measurement of the osmotic pressure 

 of solutions. (For previous reports see Year Books Nos. 2-10.) $4,000 



It had previously been shown that, between o° and 25 °, all solutions of 

 cane sugar, including that in which a gram-molecular weight of the substance 

 is dissolved in 1,000 grams of water, obey quite exactly the law of Gay- 

 Lussac for gases. More concentrated solutions have not been investigated. 

 On the other hand, there was no evidence in the conduct of the solutions 

 between these temperatures bearing on the relation of osmotic pressure to 

 the law of Boyle for gases. The osmotic pressures of the ten concentrations 

 of solution which were investigated were all in excess of the calculated gas- 

 pressures of the solute in amounts varying from 6 to 11.5 per cent of the 

 latter; and in general the osmotic pressures were not proportional to the 

 supposed concentration of the solutions. This lack of proportionality of 

 osmotic pressure to concentration was not to be accepted as proof that the 

 law of Boyle does not apply to cane-sugar solutions between o° and 25 °, 

 because it can be explained by supposing the existence of hydrates between 

 these temperatures, the formation of which would have the effect of con- 

 centrating the solutions. It was therefore important to investigate the same 

 solutions at temperatures above 25 ° ; since it was probable that, at higher 

 temperatures, any complex relations, due to the appropriation of portions 

 of the solvent by the solute, would become more simple. 



The work of measuring the osmotic pressure of cane-sugar solutions at 

 comparatively high temperatures has been in progress during the past year. 

 It was found that the ratios of osmotic to calculated gas-pressure, which are 

 constant, but apparently excessive, for each concentration between o° and 

 25 , begin in all cases to decline at some temperature between 25 and 30 . 

 In this connection, two questions were to be answered : 



(1) At what temperature does the osmotic pressure of each of the ten 

 concentrations of solution become equal to the calculated gas-pressure of 

 the solute? 



(2) When, at some temperature, the osmotic and the calculated gas- 

 pressures of the solute have become equal, is the same relation maintained 

 at all higher temperatures ? 



