SOME CRYOSCOPIC AND OSMOTIC DATA.i 



WALTER E. GARREY. 



Subsequent to the publication in 1905 of data on "The Osmotic 

 Pressure of Sea Water and the Blood of Marine Animals, etc.," (i) 

 the author has had occasion in the course of his other investiga- 

 tions, to make numerous determinations of the freezing point of 

 various sea waters, solutions and bloods; this method having 

 been used to check up other methods of obtaining solutions of 

 known osmotic pressures. Some of the data thus acquired have 

 been correlated, and although somewhat fragmentary, they are 

 published in hopes that they may facilitate the work of other 

 biologists. 



The determinations have been made with the Beckmann 

 apparatus and a differential thermometer, which could be read 

 accurately to 0.005° C. When it is remembered that the de- 

 pression of the freezing point (A) of a gram-molecular solution of a 

 non-electrolyte is (theoretically at least) 1.85° C. below zero, 

 that this depression corresponds with an osmotic pressure of 22.4 

 atmospheres (at 0° C), and that the osmotic pressures vary di- 

 rectly with the depression of the freezing point, it is seen that the 

 osmotic pressure of any solution may be calculated from the 

 simple formula: osmotic pressure = 22.4 a. A/1.85. 



Sea Waters. 



Sea waters are not solutions of absolutely fixed chemical com- 

 position, nor have they a constant concentration. While the 

 ratios of certain salts are quite constant, there are other variations 

 such as the content of absorbed oxygen and carbon dioxide and 

 even of the fixed carbonates. J. Loeb (2) has called attention to 

 the fact that the free alkalinity, i. e., the number of HO ions, is 

 distinctly higher in the sea water at Woods Hole than at Pacific 

 Grove. 



1 From the Physiological Laboratory of Washington University, St. Louis. 



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