CHEMISTRY OF THE PROTEIDS CHAP. 



neutral again by neutralising the solution. They become much more 

 readily insoluble, i.e. denaturalised, than the albumins by precipitation 

 with acids or by dialysis, and therefore they are only completely re- 

 soluble immediately after being precipitated. 



According to Osborne, 1 the hydrogen-ions of the water are the cause 

 of the globulins becoming insoluble, and this would account for coagu- 

 lation occurring more quickly in the presence of C0 2 or small amounts 

 of other acids than in pure water. Osborne calls the globulin edestin 

 after it has become insoluble, edestan, and proposes to call the deriva- 

 tives of other globulins by analogous names. Edestan is said to 

 possess a different acid-capacity from edestin. 



The precipitability of globulins by means of acids and their solu- 

 bility in alkalies depend on the fact that they themselves are acids, 

 which with litmus give an acid reaction and which liberate CO 2 

 (J. Starke). 2 They must not, however, be confounded with the acid- 

 albumins (J. Starke). 3 



Kutscher 4 observed that deutero-albumoses cause a precipitate in 

 a solution of sodium globulinate, and Hammarsten 5 has further shown 

 that sodium globulinates are precipitated by neutral salts and small 

 amounts of sodium carbonate. 



Globulins are salted out completely by saturated magnesium- 

 sulphate solutions, and partially also by saturated sodium-chloride 

 solutions ; for neutral ammonium sulphate the limits for serum-globulin 

 lie between 2 '9 and 4'6, and other globulins behave similarly; all 

 globulins are completely precipitated by half-saturated ammonium- 

 sulphate solutions, and occupy in this respect a position midway between 

 the albumins which are more difficult to precipitate, and fibrinogen and 

 casein, 6 which are more readily precipitable. 



Globulins are obtained as a precipitate by either saturating a 

 solution containing globulins, with neutral magnesium sulphate, ac- 

 cording to Hammarsten, or by adding to the serum an equal quantity 

 of cold-saturated, neutral ammonium-sulphate solution, according to 

 Hofmeister. This precipitate is dissolved in water some sodium 

 chloride being added, if necessary and the globulin -solution is then 

 either greatly diluted with distilled water, or the salts are removed by 



1 T. B. Osborne, Zeitschr. f. physiol. Chem. 33. 225 (1901). 



2 J. Starke, Zeitschr. f. Biol 40. 419 (1900). 



3 J. Starke, ibid. 40. 494 (1900) ; L. Moll, Hofmeister's Beitrdye, 4. 563 (1903). 



4 F. Kutscher, Zeitschr. f. physiol. Chem. 23. 115 (1897). 



5 0. Hammarsten, P/luger's- Arch. f. d. ges. Physiol. 18. 38 (1880) ; Zeitschr. f. 

 physiol. Chem. 8. 467 (1884). 



6 G. Kauder, Arch. f. experim. Path. u. Pharm. 20. 411 (1886) ; J. Pohl ibid. 

 20. 426 (1886). 



