Table 1 63. 



OSMOSE. 



The follow-ing table given by H. de Vries* illustrates an apparent relation between the isotonic coefficientt of solu- 

 tions and the corresponding lowering of the freezing-point and the vapor pressure. The freezing-points arc taken 

 on the authority of Raoult, and the vapor pressures on the authority of Tammann.J 



Table 1 64. 



OSMOTIC PRESSURE. 



The following numbers give the result of Pfefier's § measurement of the magnitude of tlie osmotic pressure for a one 

 per cent sugar solution. The result was found to agree with that of an equal molecular solution of hydrogen. 

 The value for the hydrogen solution is given in the third column of the table. 



* "Zeits. fiir Phys. Chem." vol. 2, p. 427. 



t The isotonic coefficient is the relative value of the molecular attraction of the different salts for water or the 

 relative value of the osmotic pressures for normal solutions. In the above table the coefificient for KNO3 was taken 

 as 3 arbitrarily and the others compared with it. The concentrations of different salts which give equal osmotic pres- 

 sures are called by Tammann and others isosmotic concentrations ; they are sometimes called isotonic concentrations. 

 The reciprocals of the numbers of molecules in the isotonic concentrations are called by De Vries the isotonic coeffi- 

 cients. 



t See also Tammann, " Wied. Ann." vol. 34, p. 315. 



§ Winkelmann's " Handbuch der Physik," vol. 1, p. 632. 



Smithsonian Tables. 



150 



