546 ; Proteins 
Comparing I and II we notice that the previous treatment 
with CaCl, did not increase the swelling of the block of gelatin. 
In the same way all the experiments on antagonistic salt action 
described in the previous paper® could be repeated with solid 
blocks of gelatin. 
These and other experiments allow us to state that the influence 
of salts upon the swelling of powdered gelatin published in the 
previous paper holds for solid blocks of gelatin also if only care 
is taken to remove the excess of salt from the block. The results 
obtained on powdered. gelatin can, therefore, be utilized for the 
theory of swelling of gelatin in general. 
V. 
Our results contradict the conclusions which are drawn by 
many authors from the old experiments of Hofmeister!’ on the 
influence of neutral salts and sugar on the swelling of gelatin. 
Hofmeister stated that the salts, according to their effect upon 
the swelling of gelatin, may be divided into two groups. ‘The one 
group makes the gelatin swell more than distilled water, the other 
makes it swell less than distilled water. The former group in- 
cludes NaBr, NaNO3, NH.Cl, NaCl, KCl. The second group 
includes the acetates, citrates, tartrates, and sulfates; but also 
alcohol, grape sugar, and cane sugar. From these observations 
it has generally been concluded that the anion is the decisive 
factor for the swelling; and that Hofmeister’s results agree with 
the influence of salts on other qualities of proteins. Such a con- 
clusion overlooks Hofmeister’s distinct statement that alcohol 
and sugars act like acetates and tartrates. This fact is of im- 
portance since it confirmed Hofmeister in his idea that the attrac- 
tion of the salt for water was one of the factors by which salts and 
sugars influence the swelling of gelatin. Thus he states that the 
sulfates, tartrates, citrates, and acetates, attract water more 
powerfully than chlorides or bromides and hence prevent the 
gelatin from absorbing as much water as it does in pure water 
or in the presence of chlorides. 
Hofmeister’s method cannot give any clear idea concerning 
the influence of salts on the swelling of gelatin since this influence 
depends chiefly upon the ionization of the gelatin. Two proc- 
13 Hofmeister, F., Arch. exp. Path. u. Pharm., 1891, xxviii, 210. 
