EARLIER INVESTIGATIONS 



109 



salts render proteins insoluble by extracting water from them. 

 This suggestion was again put forward in 1888 by F. Hofmeister 

 (30), who, together with his pupils, advanced in the immediately 

 succeeding years, a number of experimental data in support of 

 his thesis (30) (31) (38) (62) (43). 



Kiihne (39) and Kauder (38), having shown that not only the 

 concentration of the added salt but also that of the protein is 

 of importance in determining the amount of salt required for its 

 coagulation, care was taken in these and in the majority of suc- 

 ceeding investigations, when comparing the coagulating power of 

 different salts, to maintain the concentration of the protein 

 constant, the procedure being to add to a given volume of protein- 

 containing fluid (e.g., blood serum) varying amounts of different 

 salt solutions, and then dilute the mixture to a standard volume. 



Lewith showed that the relative efficacy of the different salts 

 which he employed in coagulating the proteins of blood serum 

 was the same for serum globulins as for serum-albumins, sul- 

 phates and acetates being more powerful coagulants than nitrates 

 or chlorides. His results have been tabulated as follows by 

 Gustav Mann (46), a (+) indicating that the salts do, and a ( ) 

 that they do not precipitate serum-albumin. 



Hofmeister, in 1888, extended and confirmed these observations, 

 employing not only serum-proteins but also egg-albumin, gelatin 

 and other colloids, namely colloidal ferric hydrate and sodium 

 oleate. He found that whatever the colloid employed the rela- 

 tive coagulating power of the various salts was the same. Excep- 

 tions to this rule were noted, however, when salts of di- or tri- 

 basic acids were employed, the order of their efficacy in coagu- 

 lating egg-globulin and gelatin being the same, but differing 



