292 Effects of Electrolytes on Gelatin. I 
In Fig. 5 the distinctness with which the salts with bivalent 
ions are separated from the monovalent salts is noteworthy. 
The effects of salts upon the alcoho! number of gelatin are 
roughly parallel to their effects on the other properties of gela- 
tin. The temperature of gelation in salt solutions has been 
measured by Levites!? and by Pauli and Rona,!8 the swelling of 
gelatin in salts by Ostwald,’ Ehrenberg,! Pascheles,!? and Lenk,?° 
and its viscosity: in salt solutions by von Schroeder.? None of © 
these methods of investigation is as simple or as accurate as the 
alcohol method and the results are correspondingly less complete. 
Pauli?! has investigated the effects of salts upon the tempera- 
ture of coagulation of egg white and finds them similar to the 
effects on the coagulation by alcohol. He finds that the bivalent 
metals are more effective than the monovalent metals in pre- 
venting coagulation. The action of salts in dispersing gelatin 
so that more alcohol is needed for precipitation is also similar 
to their effects in dispersing globulin. Thus Mellanby”? has_ 
found that the dispersing efficiency of trivalent, bivalent, and 
monovalent ions were to each other as the squares of their va- 
lenees, and the efficiency of salts were equal to the sum of the 
efficiencies of their separate ions. Thus the dispersing efficiencies 
of NaCl, CaChk, Na.SO,, and MgSO, are 2, 6, 6, and 8 respec- 
tively. This conclusion is borne out by the alcohol experiments 
except for the fact that salts like MgSO, have very much less 
effect on gelatin than NaCl, instead of four times as much. 
The effects of salts upon the physical properties of proteins 
are now known to be accompanied by a combination of the salt 
with the protein, although Bugarsky and Liebermann” were un- 
able to find any evidence of it in the case of NaCl and egg white 
by their measurements of the freezing point or the electro- 
metric determination of the Clion. Hardy* has shown by con- 
ductivity measurements that NaCl combines with globulin to the 
17 Levites, S. J., Z. Chem. u. Ind. Kolloide, 1907-08, ii, 237. 
18 Pauli, W., and Rona, P., Beitr. chem. Physiol. u. Path., 1902, ii, 1 
19 Pascheles, W., Arch. ges. Phystol., 1898, lxxi, 333. 
20 Lenk, E., Biochem. Z., 1916, xxiii, 15. 
21 Pauh, Arch. ges. Physiol., 1899, Ixxviii, 315. 
2 Mellanby, J., J. Physiol., 1905-06, xxxili, 338. 
23 Hardy, W. B., J. Phystol., 1905-06. xxxiii, 251. 
