268 



ION SERIES AND PROTEINS. II 



These data lend no support to the assumption that the difference 

 between the swelling, viscosity, and osmotic pressure of gelatin sulfate 

 on the one hand, and of gelatin chloride and gelatin oxalate on the 

 other is due to differences in the degree of ionization of proteins. 



TABLE VI. 



Specific Conductivity of 1 per cent Solutions of Gelatin Chloride, Gelatin Sulfate, 



and Gelatin Oxalate. 



SUMMARY AND CONCLUSIONS. 



1. Our results show clearly that the Hofmeister series is not the 

 correct expression of the relative effect of ions on the swelhng of gela- 

 tin, and that it is not true that chlorides, bromides, and nitrates have 

 ''hydrating," and acetates, tartrates, citrates, and phosphates "de- 

 hydrating," effects. If the pH of the gelatin is taken into consider- 

 tion, it is found that for the same pH the effect on swelling is the same 

 for gelatin chloride, nitrate, trichloracetate, tartrate, succinate, oxa- 

 late, citrate, and phosphate, while the swelHng is considerably less for 

 gelatin sulfate. This is exactly what we should expect on the basis 

 of the combining ratios of the corresponding acids with gelatin since 

 the weak dibasic and tribasic acids combine with gelatin in molecular 

 proportions while the strong dibasic acid H2SO4 combines with gelatin 

 in equivalent proportions. In the case of the weak dibasic acids he 

 anion in combination with gelatin is therefore monovalent and in 

 the case of the strong H2SO4 it is bivalent. Hence it is only the 

 valency and not the nature of the ion in combination with gelatin 

 which affects the degree of swelling. 



2. This is corroborated in the experiments with alkalies which 

 show that LiOH, NaOH, KOH, and NH4OH cause the same degree 

 of swelling at the same pH of the gelatin solution and that this swell- 



