HISTORICAL INTRODUCTION 13 



charges of micellae by neutral salts depends on the fact that 

 proteins combine stoichiometrically with acids and alkalies 

 forming true ionizable salts. The agreement between calculated 

 and observed values is so close that there is neither any need nor 

 room for speculations on adsorption, unless it can be shown that 

 the adsorption hypothesis furnishes an equally good mathematical 

 and quantitative agreement between observed and calculated 

 P.D. 



4. THE HOFMEISTER ION SERIES 



Hofmeister 1 was the first to investigate the effects of different 

 salts on the physical properties of proteins. He and his followers 

 observed that the relative effects of anions on the precipitation, 

 the swelling, and other properties of proteins seemed very definite 

 and that the anions could be arranged apparently in definite 

 series according to their relative efficiency, the order being 

 independent of the nature of the cation. Similar series were also 

 found for the cations, though these series seemed to be less 

 definite. These Hofmeister series were a puzzle to those who 

 accepted the chemical viewpoint of the behavior of proteins, inas- 

 much as it was impossible to discover in these series a relation to 

 the typical combining ratios of the ions. 



To illustrate this we will quote the order which, according to 

 Pauli, 2 represents the relative efficiency of different acids on the 

 viscosity of blood albumin, 



HC1 > monochloracetic > oxalic > dichloracetic > 

 citric > acetic > sulphuric > trichloracetic acid, 



where HC1 increased the viscosity most and trichloracetic or 

 sulphuric least. In this series the strong monobasic acid HC1 is 

 followed by the weak monochloracetic acid, this is followed by 

 the dibasic oxalic acid ; later follows the weak tribasic citric acid, 

 then the very weak monobasic acetic acid, then the strong dibasic 

 sulphuric acid, and finally again a monobasic acid, trichloracetic. 

 According to Hofmeister, gelatin swells more in chlorides, 



1 HOFMEISTER, F., Arch. exp. Path. u. Pharm., vol. 24, p. 247, 1888; 

 vol. 25, p. 1, 188&-89; vol. 27, p. 395, 1890; vol. 28, p. 210, 1891. 



2 PAULI, W., Fortschr. naturwiss. Forschung, vol. 4, p. 223, 1912. 



