New York AGRICULTURAL EXPERIMENT STATION. eae 
The solvent power of the dilute solutions, at least of hydro- 
chloric and sulphuric acids, appears, “herefore, to depend upon 
the presence of H* ions. However, since the solvent power of 
lactic acid is comparable with that of the mineral acids, it sug- 
gests that, other conditions being uniform, the concentration of the 
H* ions is not the only factor. As bearing on this point, there is 
desirable a quantitative test of the solubilities of casein in acids of 
variable dissociating powers. 
The following figures represent the percentage of dissociation 
and, according to the dissociation theory, the relative concentration 
of the H* ions in solutions of the four acids of the concentrations 
used : 
Percentage of dissociation. 


Equivalent — ——— 
volume. Hydro- 
chloric. Sulphuric. Lactic. Acetic. 
LES os ee igs AS On a 100 82 ee fulgnd 
SUD, Cape ES ere ae Ne Ppa ae TOO 95 22.7 Ort 
NOES ao AR Ce cue aoe eran Caer arena 100 98 20, 7a Lome 
The figures for hydrochloric and sulphuric acids are according 
to Jones and Douglas; those for lactic and acetic acids, from 
Ostwald.” 
The results presented in Tables V, VI and VII show that hydro- 
chloric acid- has stronger solvent power than sulphuric acid and that 
lactic is stronger than acetic, results which are in general accord 
with the dissociation figures preceding, so far as the two mineral 
and the two organic acids, taken separately, compare with each 
other ; but the dissolving power of the two organic acids, compared 
with that of the mineral acids, is entirely out of proportion to the 
relative dissociating powers of the former. Apparently the anions 
of the organic acids as well as the H* ions influence the solvent 
power. This solvent effect of the organic ions is also shown by 
Robertson’s® results. While he found that N-10 solutions of the 
chloride, sulphate and nitrate of sodium did not dissolve casein 
appreciably, the acetate, propionate, butyrate and valerate all 
showed marked solvent action. 
* Amer. Chem. Jour., 26:434. 1901. 
* Ztschr. Phys. Chem., 3:174 and 191. 1880. 
sJour. Biol. Chem, 2:35>. 
