EARLIER INVESTIGATIONS 



111 



In 1898 Pauli (51) (58) published the results of a number of 

 investigations upon the influence of various salts on the gelatin- 

 izing- and melting-temperatures of gelatin solutions. He found 

 that effects of different salts upon the gelatinizing and melting 

 of strong gelatin solutions ran parallel with their power of coagu- 

 lating gelatin and of inhibiting the swelling of gelatin plates. 

 Thus chlorides, bromides, and iodides of potassium, sodium, am- 

 monium and magnesium lower the temperatures of gelatinization 

 and of melting, in the following order, the most effective being 

 placed first.* 



Sodium sulphate, magnesium sulphate, sodium citrate, ammo- 

 nium sulphate, magnesium sulphate, sodium tartrate, sodium 

 acetate. The following is the order in which these salts bring 

 about the coagulation of gelatin, the most effective- being, placed 

 first: 



Sodium sulphate, potassium sulphate, sodium citrate, mag- 

 nesium chloride, sodium tartrate, magnesium sulphate, ammonium 

 sulphate, sodium acetate^ potassium chloride, sodium chloride. 



There is evidently a close, although not an absolute parallel- 

 ism between the two series. Urea and alcohol lowered, but 

 glycerin markedly raised the temperatures of gelatinization and 

 of melting. 



In a later communication (52) Pauli showed that the order in 

 which various salts affect the coagulation-temperature of egg- 

 globulin is similar to that in which they occur in the above series. 

 The following table, cited after Pauli, gives the order in which 

 the various salts bring about the transformation of the proteins 

 from the dissolved into the solid condition: 



All of these substances were employed in equimolecular solutions. 



