96 PROTOPLASMIC ACTION AND NERVOUS ACTION 



positivity of any surface, whatever its chemical composi- 

 tion, was invariably increased by adding monovalent 

 acid to the solution, and decreased by adding monovalent 

 base. Polyvalent ions were very effective, reversing 

 the sign of the partition-charge in extremely low con- 

 centrations; e.g., for a partition of chromic chloride 

 these results were found. 



Solution 4'^^^/^ Flow 



Water slightly acid -f 59 



Same-f .001 n K^Fe (CN)6 ... + 2 



Same-|-.02 n K^Fe (CN)6. ... — 20 (reversal) 



Freundlich^ calculated from Perrin's data the con- 

 centration of salts (millimols per litre) required to reduce 

 by 50 per cent the endosmose through positive and nega- 

 tive partitions, respectively, and obtained the following 

 results. 



I. CrClj (positive) Cone, (millimols per litre) for 



Solution 1/2 velocity 



Dil. acid-f KBr 60 



Same-hMgS04 i 



Same-hK3Fe(CN)6 o. i 



II. Carborundum (negative) Cone, for 1/2 velocity 

 Soluiioji 



Dil. alkali-f-NaBr 50 



Same-|-Ba(N03)2 2 



Same-|-La(N03)3 o. i 



The effect thus increases very rapidly, in accord- 

 ance with Schulze's rule, with increase in the valence 

 of the active ion, which is always that having the opposite 

 sign to that of the partition. EUissafoff^ in an investiga- 



* Kapillarchemie, p. 238. 



» Ellissafoff, Z. physik. Chem., LXXIX (191 2), 385. 



