W. O. Fenn 451 
The effect of NaCl on gelatin dissolved in NaOH is shown in 
Fig. 6 and Table VI. The effect of NaCl on pure gelatin is a 
gradual increase in the alcohol number, as shown by the dotted 
line. Its effect on gelatin made up in NaOH, 0.015 M, is to de- 
crease the alcohol number until a minimum is reached, after 
TABLE VI. 
Antagonism between NaCl and NaOH in Their Effects on Gelatin. 
Ce. alcohol to precipitate in gelatin plus 
Concentration of NaCl. 
H:2O NaO8, 0.015 m 
M 
0.25 8.0 8.45 
0.125 ; 6.85 8.05 
0.0625 6.15 78 
0.0312 8.1 
0.0156 9.0 
0.0 4.4 10.4 
3 per cent gelatin B. Stood over night at 26°C. before adding alcohol. 
Other details as in Table I. (See Fig. 6.) 
which the alcohol number increases gradually as in the pure 
NaCl curve. This shows antagonism because the combined 
effect of NaOH and NaCl is less than the effect of one of the 
electrolytes (NaOH) alone. 
SUMMARY. 
1. Monovalent salts (like NaCl) are antagonistic to both acids 
and alkalies in all concentrations. 
2. Salts with bivalent cations (like CaCl.) are antagonistic to 
alkalies but not antagonistic to acids (except in high conceh- 
trations). 
3. Salts with bivalent anions (like NagSO.) are antagonistic to 
acids but not antagonistic to alkalies except in high concentra- 
tions when the greater the concentration of either alkali or salt, 
the less the alcohol necessary for precipitation. 
