198 BIO-CHEMICAL JOURNAL 



This is very nearly the same as that found by Pauli 1 in the case 

 of precipitation of proteins. 



It is a matter of some interest to see whether in this case of 

 adsorption the anions have a retarding action like that shown by Pauli 

 in the above-mentioned experiments. That there is some action of 

 this kind can I think be shown by consideration of the comparative 

 action of chloride and sulphate of the same metal, say potassium. The 

 difficulty lies in the fact of the great preponderance of the opposite 

 action of the kation, probably on account of the negative charge of 

 the congo-red. If we take equimolecular solutions of K.CI and K 2 so 4 

 we find their effect almost exactly the same within limits of experi- 

 mental error. Now there are, in the dilute solutions employed, very 

 nearly twice the number of kations in the K,so 4 than in that of the 

 KCI, necessarily, therefore, the so t ion has a greater retarding power 

 than the ci ion. In determining the order of the anions in this respect 

 the same difficulty presents itself, as in the case of the opposite effect 

 of the kations, but in a more marked degree. The approximate order 

 as regards power of inhibition is the following : 



OH < CNS < acetate < Cl < F < oxalate < SO 4 < PO 4 



The results of these experiments will be best shown in a table 

 analogous to those given by Pauli. The numbers give the percentage 

 amount of dye adsorbed at room temperature under the influence of 

 the body formed by the combination of kation and anion shown 

 vertically above and horizontally at the left-hand side of each number, 



and in concentration. 



200 



CONGO RED 

 H Li K Na NH 4 Mg Ca 



OH 26 58 ... 68 79 (Y Z ) 89 



CNS ... . 6 4 86 



Acetate ... ... 58 70 81 



Cl ... 7 75 72 9 1 



F 75 



Oxalate 12 ... 80 65 



so. 4 7i 74 78 78 9 1 > IO 



P0 4 74 



1. Hofmeister's Beitrage, III, p. 225 ; V, p. 27 ; VI, p. 233 ; and VII, p. 531. 



