Jacques Loeb 547 
esses are necessary to obtain the correct estimate of the effect of 
this ionization; first, treatment of the whole mass of gelatin with 
a sufficiently high concentration of the neutral salt (m/8 or M/4), 
and such a treatment can only be effective if the protein is in — 
finely divided condition; and second, removal of the excess of 
salt in order to permit the electrolytic dissociation of the protein. 
Neither condition is fulfilled in Hofmeister’s method. This also 
explains why he got similar results with sugar and alcohol as 
with sodium acetate and sodium sulfate. The differences Hof- 
meister observed in the action of different salts are comparatively 
slight and they cannot be used for a theory of the action of salts 
on swelling. 
Lenk" tried to demonstrate the ptseoniene action Peace 
NaCl and CaCl: on gelatin. He used Hofmeister’s method, try- 
ing to show that blocks of gelatin swell less in NaCl solution 
when CaCl, is added, but the effects observed are small and, 
as the writer believes, within the limits of error of such ex- 
periments. Fenn" tried to show that gelatin solutions require 
less alcohol for precipitation in the presence of NaCl when CaCl, 
is added. This is a much more promising method for the study of 
antagonistic salt action than the one used by Lenk, but the re- 
sults of Fenn published in his preliminary notices show that he 
also studied the effects of salts on protein without first removing 
the excess of salt so that he missed the ionization effect. 
Theoretical Remarks. 
The paper gives a new and convenient method for the investi- 
gation of the effects of electrolytes on the physical properties of 
proteins and other so called colloids. This method leads to en- 
tirely different results from those obtained by the old method of 
Hofmeister on the swelling of gelatin, and this difference is due to 
the fact that in Hofmeister’s method the effect of the salt on 
swelling is observed in the presence of an excess of salt, which, as 
our method shows, inhibits the additional swelling effect of the 
salt. This latter is the only characteristic effect of the salt on 
the swelling. Hence it is not possible to discover by Hofmeister’s — 
144 Tenk, E., Biochem. Z., 1916, Ixxiii, 15, 58. 
15 Fenn, W. O., Proc. Nat. Acad. Sc., 1916, ii, 534, 539. 
