294 Effects of Electrolytes on Gelatin. I 
des Bancels,®® von Elissafoff,*! and others; and the work of Bose® 
and Guillaume® on the potential developed when a gelatin- 
coated wire is suddenly twisted in the solution of an electrolyte. 
Contrary evidence is found, however, in the fact that neither 
Chick** nor Hardy” were able to find any convection of globulins 
(or of gelatin) in solutions of the alkaline earths. Whatever dif- 
ference there is, therefore, in the extent to which the cations and 
anions of the alkaline earths combine with proteins must be too 
small to detect except by the most delicate measurements of the 
change in the H ion concentration. The difference would of 
course be still less in the case of the salts of the alkali metals, 
SUMMARY. 
1. Acids and alkalies hinder the precipitation of gelatin by 
alcohol. In the case of strong acids and alkalies this effect passes 
through a sharp maximum and then decreases. 
2. Increasing concentrations of salts tend to hinder the precipi- 
tation of gelatin by alcohol until.a maximum is reached, trivalent 
ions being more effective than bivalent, and bivalent more effective 
than monovalent in this respect. 
3. Certain salts (like MnSO,) which combine a bivalent cat- 
ion with a bivalent anion are exceptions to this rule in that they 
either assist or only very slightly hinder the precipitation of gela- 
tin by alcohol, the effect of one ion being apparently neutralized 
by that of the other. 
4, Salts like AlCl; and CuCl which are very effective in hin- 
dering precipitation by alcohol resemble the strong acids in that 
their effect passes through a maximum and then decreases. 
5. The effect of the sulfates, citrates, and tartrates of the 
alkali metals also decreases in high concentrations due to their 
strong ‘‘salting out’? or dehydrating powers. 
30 des Bancels, J. L., Compt. rend. Acad., 1909, cxlix, 316. 
31 von EHlissafoff, G., Z. physikal. Chem., 1912, lxxix, 385. 
2 Bose, J. C., J. phys. théorique et apliquée, 1902, series 4, i, 481. 
33 Guillaume, E., Compt. rend. Acad., 1908, exlvii, 53. 
34 Chick, H., Biochem. J., 1913, vii, 318. 
