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CARNEGIE INSTITUTION OF WASHINGTON. 



and its support so that the osmotic pressure of solutions other than 

 a few non-electrolytes could be measured. 



The work on the first of these problems has been successful, as it 

 has been shown that the water interferometer permits accurate 

 and rapid measurements of the osmotic pressure of solutions. Thus 

 the following results have been obtained on solutions of sucrose at 30° 

 and 55.7°: 



The important feature of this work is that measurements have been 

 made under conditions where there has been no passage of the solute 

 into the solvent through the membrane. The point of most interest 

 in the results is the temperature coefficient of these concentrated solu- 

 tions. In the most concentrated solutions studied, it has been found 

 that the temperature coefficient is not only less than that of an ideal 

 gas, but so much less that the osmotic pressure of some of the most 

 concentrated solutions is actually less at 55.7° than at 30°. Efforts 

 are being made to extend these measurements to temperatures higher 

 than 55.7°. 



Noyes, Arthur A., California Institute of Technology, Pasadena, California. 

 Researches upon (1) the properties of solutions in relation to the ionic theory, 

 and {2) the determination of the atomic structure of crystalline substances 

 by X-rays. (For previous reports see Year Books Nos. 2-18.) 



Efforts during the past year have been primarily directed to prepar- 

 ing for publication the various researches completed during the war 

 period ; and seven articles describing these researches have been pub- 

 lished in current journals. 



The most important general result to which these researches have 

 led is the substantiation of the principle that the ratio of the equivalent 



