W. O. Fenn 283 
Similar curves have been worked out for various other acids. 
Lactic, trichloroacetic, acetic, and formic acids give curves which 
rise more gradually than the HCl curve. It is impossible to fol- 
low them through the maximum as no precipitate can be ob- 
tained. Phosphoric acid gives a sharp fall after the maximum 
which can be followed, but no precipitate can be obtained at the 
maximum. ‘Tartaric acid and sulfuric acid rise slowly to a com- 
paratively low maximum and do not drop thereafter. In gen- 
eral, the weak acids have less effect and show either no maximum 
or less maximum than the HCl curve. The small effect of 
H.SO., compared to HCl and HNOs, is probably due to the effect 
of the bivalent SO, anion. 
The fact that acids and alkalies prevent the precipitation of 
proteins by alcohol was shown by Pauli and Handovsky? and by 
Schorr,* although in neither case was the complete course of the 
curve worked out. Pauli and collaborators,® Lacqueur and Sackur,® 
and Zoja’ have shown that acids and alkalies increase the viscosity 
of protein sols, and von Schroeder? has shown the same for gelatin 
sols. Theswelling of gelatin has been measured by Ostwald,® Proc- 
ter,® Fischer,!® and Ehrenberg.!! The characteristic maxima in 
both acids and alkalies, as found by these workers, correspond to 
the maxima of the alcohol curves as found by the writer. Ost- 
wald, however, finds in addition an initial minimum (in swelling) 
which is more pronounced in acids but discernible in alkalies also. 
In spite of the overwhelming evidence to the contrary of Pauli 
and his pupils, he attempts to homologize this minimum with 
3 Pauli, W., and Handovsky, H., Biochem. Z., 1909, xviii, 340. 
4 Schorr, C., Biochem. Z., 1911, xxxvii, 424. 
5 Pauli, W., Chem. wu. aan Relleries 1908, iii, 2; 1910, vii, 241: 1918, 
4 Fee ar ad bee Barada Soc., 1913, ix, 54. Pauli, W., and Wagner, R., Bio- 
chem. Z., 1910, xxvii, 296. Pauli, W., and Falek, O., ibid., 1912, arn. 269. 
6 Lacqueur, E., and Sackur, O., Beitr. chem. Physiol. u. Path., 1903, 
‘ii, 193. 
7Zoja, L., Z. Chem. u. Ind. Kolloide, 1908, i111, 249. 
8 Ostwald, W., Arch. ges. Phystol., 1905, cviii, 563; cix, 277; 1906, cxi, 
581; Tr. Faraday Soc., 1913, ix, 34. 
® Procter, H. R., Kolloidchem. Bethefte, 1910-11, ii, 243. Procter, H. R., 
and Wilson, J. A., J. Am. Leather Chem. Assn., 1916, xi, 261. Procter, J. 
Chem. Soc., 1914, ev, 313. Procter and Wilson, ibid., 1916, cix, 307. 
10 inesher, M. H., G@idema and Nephritis, New York: 2nd edition, 1915. 
11 Khrenberg, R.., Fava Z., 1913; liu, 356. 
