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OSMOTIC PRESSURE OF AQUEOUS SOLUTIONS. 



The foregoing measurements of the osmotic pressure of glucose indi- 

 cate that, between 30° and 50°, the aqueous solutions of this substance 

 obey the gas laws, since — if we employ the weight or solvent normal 

 system in making the solutions, and refer the theoretical gas pressure 

 of the solute to the volume of the pure solvent — the ratio of observed 

 osmotic to calculated gas pressure is, in all cases, approximately unity. 

 Stated in another way, the equation of van't Hoff for very dilute 

 solutions, PV = KT, applies to concentrated solutions of glucose between 

 30° and 50°, provided we allow the V to signify the volume of the pure 

 solvent, instead of the volume of the solution. 



The osmotic pressure of glucose, and also of cane sugar, will be meas- 

 ured at 60°, 70°, 80°, and, if possible, at still higher temperatures. 



