32 THE VEGETABLE PROTEINS 



iodides but more energetic than the chlorides. Barium and calcium 

 bromides were equal to one another in solvent power, but this was less 

 than that of sodium or potassium iodide and greater than that of sodium 

 or potassium bromide, the two latter being somewhat less powerful 

 solvents than the corresponding chlorides. Lithium bromide was a 

 much better solvent than lithium chloride, but less energetic than either 

 sodium or potassium bromide. 



Salts of strong bases with weak acids which are dissociated in solu- 

 tion with an alkaline reaction had a solvent power approximately pro- 

 portional to their hydrolytic dissociation. Sodium sulphite and sodium 

 thiosulphate were alike in their solvent power, both being much better 

 solvents than the sulphates. Potassium chromate dissolved edestin 

 more readily than did either the sulphite or the thiosulphate, and was 

 but little less powerful in its solvent effect than sodium carbonate. 



Salts of weak bases with strong acids, which are hydrolytically dis- 

 sociated with an acid reaction, had a less solvent power than those of 

 strong bases with strong acids, corresponding in this respect to their 

 hydrolytic dissociation. Thus manganese chloride, manganese sulphate 

 and ferrous sulphate dissolved edestin to about the same extent as did 

 sodium chloride, having, therefore, about one-half the solvent power of 

 salts of strong bases with strong acids, the two manganese salts being, 

 in fact, better solvents than ferrous sulphate. 



Solutions of acetates behave anomalously, for the acetates of potas- 

 sium, sodium or ammonium had no solvent action at 20 on edestin, 

 while those of manganese, barium, strontium, calcium and magnesium 

 dissolved it freely, the degree of solubility in solutions of each of these 

 acetates being in the order named. In solutions of acetates of lead, 

 copper and silver, which are commonly supposed to be precipitants of 

 proteins, edestin, in the complete absence of other salts, dissolves almost 

 as freely as it does in solutions of pure acetic acid. The solvent power 

 of each of these metallic acetates is equal, and evidence was obtained 

 which showed that the metallic ion of the acetate was united in organic 

 combination with the protein. The solvent effect of lead, copper and 

 silver acetates is manifestly due to a different reaction with the protein 

 than that which takes place when the protein is brought into solution 

 by means of any of the other salts previously mentioned. Solutions 

 of edestin, produced with each of these other salts, are precipitated by 

 dilution, but those made with solutions of lead, copper or silver acetate 

 are not, behaving in this respect like those made with free acid. 



The degree of solubility of edestin is influenced by the amount of 

 the acid which is united with the preparation to form an edestin salt. 



