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. 



So'^'i- D^fem Flow 



Water slightly acid + 59 



Same-h.ooi n KjFe (CN)6 ... + 2 



Same-|-.o2 n K3Fe (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. CrCl3 (positive) Cone, (millimols per litre) for 



Solution 1/2 velocity 



Dil. acid+KBr 60 



Same-f MgS04 i 



Same-l-K3Fe(CN)6 o. i 



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

 Solution 



Dil. alkali-hNaBr 50 



Same-hBa(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. Ellissafoff^ in an investiga- 



^ K a pillar chemie, p. 238. 



^ EllissafoJBf, Z. physik. Chem., LXXDC (191 2), 385. 



