CHEMISTRY. 293 



always somewhat less. The viscosities of solutions of salts in these 

 solvents are always greater than those of the solvents themselves, the 

 increments being less in the case of the non-hydrated salts of the alkalis 

 than of the hydrated salts of the alkaline earths. 



Morse, H. N., and J. C. W. Frazer, Johns Hopkins University, Baltimore, 

 Maryland. Measurement of the osmotic pressure of solutions. (For pre- 

 vious reports see Year Books Nos. 2-15.) 



Recently, the method of measuring osmotic pressure has been devel- 

 oped so that it is possible to measure the osmotic pressure of quite con- 

 centrated solutions. This method also greatly reduces the time which, 

 heretofore, has been necessary to reach the equilibrium pressure of a 

 solution. The results of this work by J. C. W. Frazer and R. T. 

 Myrick, on "The osmotic pressure of sucrose solutions at 30°," have 

 been published in the Journal of the American Chemical Society, 

 XXXVIII, page 1907 (1916). During the past year this method of 

 measuring pressures has been used in the investigation of the osmotic 

 pressures of glucose solutions. Before undertaking this investigation 

 it was decided to alter the apparatus in such a way that the solution 

 could be stirred continuously, or at intervals, during the course of the 

 experiment. One of the objects of this change was to ascertain if such 

 agitation of the solution had anj^ effect on the final equilibrium pres- 

 sure or on the velocity with which this equilibrium pressure is reached. 

 The results showed that agitation of the solution produced no difference 

 in the final equilibrium pressure. No conclusion was reached as to the 

 effect of agitation on the time required to reach the equilibrium pressure 

 of a solution. This was probably because it was necessary to enlarge the 

 capacity of the apparatus to accommodate the stirring device and there 

 was consequent!}^ greater compression of the cell contents, necessitat- 

 ing a correspondingly greater intake of solvent through the membrane. 



^leasurement of the osmotic pressure of glucose solutions was under- 

 taken to secure data over a wide range of concentration extending to 

 saturation and at more than a single temperature. The work was begun 

 by repeating the measurements on concentrations from 0.1 to 1.0 molar. 

 The table on the next page summarizes these results on concentrations 

 above 0.5 molar. 



The measurements on concentrations up to 3.0 molar were made with 

 glass monometers and with equipment described in the Journal of the 

 American Chemical Society, xxxviii, 1907 (1916); the measurements 

 on the more concentrated solutions were made by the "resistance gage" 

 described in the same publication. 



The measurements were made at three different temperatures to 

 obtain information on the influence of the heat of dilution on the tem- 

 perature coefficient of osmotic pressure. The results are in general 

 satisfactory and in accord with theoretical considerations. 



The above results on the more concentrated solutions obtained by the 

 "resistance gage" are not free from suspicion, since the gage coil has 



