8o 



WALTER E. GARREY. 



by the author; when not given they may be approximated by 

 interpolation.^ 



Table III. 



Cane Sugar. 



Attention should be directed to a fact to which Jones (4), 

 Morse and Fraser and Berkeley and Hartley have called atten- 

 tion, viz., that cane sugar solutions show osmotic pressures 

 considerably in excess of what theory would lead one to expect. 

 Loeb has shown the importance of this fact for biological work (5). 

 From purely theoretical considerations one would expect a molar 

 (gram-molecular) solution to show an osmotic pressure only 

 slightly in excess of that of Woods Hole sea water. Loeb found 

 that it caused a shrinkage of the eggs of the echinoderms even of 

 the Pacific, and his experiments caused him to select 6/8 m. cane 

 sugar as the proper concentration for the development of Stron- 

 gylocentrotus purpuratus. The osmotic pressure of Woods Hole 

 sea water by calculation from the freezing point is 21.9 a. (at 

 0° C), a figure which is almost identical with that obtained by 



1 The determinations of Gerlach for NaCl and KCl {Chemiker-Kalender, 1914, L, 

 p. 261) and of Schiff for MgCl and CaCh {ibid., p. 265) show, that, for concentra- 

 tions of solutions of the magnitudes with which we are dealing and in which these 

 salts are present in sea water, the densities are a linear function of the concentration. 

 A plat of our determinations shows the same to be true for both densities and 

 freezing points of dilutions of sea water. 



