JACQUES LOEB 



279 



of the initial rate of diffusion, as well as of the permanent osmotic 

 pressure with the increase in the concentration of the salt added. 

 The drop is more rapid when Ca is added than when K is added, as 

 it should be on account of the fact that the particles of water 

 diffusing through the membrane are positively charged. 



200 



o 

 'in 



•1—1 



Ji n n. n n u. u n H 



2000 1000 500 250 125 62 31 15 7 



Concentration of salt added 



Fig. 3. Depressing effect of the addition of neutral salt to a 1 per cent solution 

 of Na gelatinate of pH about 8.4 upon the initial rate of diffusion of water into 

 the solution during 30 minutes. Abscissae are the concentration of salt added, 

 ordinates the height of level of liquid in manometer after 30 minutes. The 

 depressing effect of Ca is greater than that of K. 



Figs. 5 and 6 show that the depressing effect of the addition of 

 alkali is the same as that of the addition of neutral salt with the same 

 cation, Ca(0H)2 causing a greater depression than KOH. This 

 contradicts the statement current in the literature of colloid chemistry 

 that salts lower and that alkahes raise the osmotic pressure of gelatin 

 solutions. 



