vin HEAT-COAGULATION 319 



precipitating the remainder. Whether salts are needed or may be 

 dispensed with will depend on the nature and the grouping of the 

 ammo-acid compounds in the albumin. 



A chemical explanation as to why acid-albumins are precipitated 

 by salts, is, according to Cohrmeim, still outstanding, but it is definitely 

 known that this phenomenon is not a salting-out process, for Panum, 1 

 Billow, 2 Werigo, 3 Kieseritzky, 4 Rosenberg, 5 Goldschmidt, 6 v. Fiirth, 7 

 Schulz, 8 Starke, 9 and Erb 10 have shown precipitation to be brought 

 about by mere traces of salt. 



The author is of the opinion that the precipitation of acid 

 albumins by the addition of salts is in every respect analogous to the 

 throwing down of colloidal solutions by ' neutral ' salts, as explained 

 on p. 289. The acid albumin + the strong an-ion radical of a * neutral ' 

 salt possess collectively the same amount of electro-affinity as does 

 the strong kat-ion of the ' neutral ' salt. This view is further supported 

 by the fact that there is a definite proportionality between the amount 

 of acid present in the albumin and the amount of salt which is 

 required to ensure precipitation. The smaller the excess of acid the 

 less salt is needed for precipitating the albumin. 



The author's theory explains also the observations of Goldschmidt 

 and others, namely, that on neutralising a strongly, acid solution of acid- 

 albumin, a localised precipitate is formed in the acid solution by the 

 addition of an alkali, and that this precipitate then dissolves, to be formed 

 again by a further addition of alkali, to redissolve, and so on; for during 

 the addition of the alkali a neutral salt is formed temporarily, and 

 this neutral salt leads to the albumin being precipitated. A complete 

 precipitation of all the acid-albumin is, however, exceedingly difficult, 

 according to Werigo, Spiro, and Pemsel, 11 as the equivalent amounts 

 of the inorganic constituents needed for the exact neutralisation of 

 an albumin with its high molecular weight are so small as to bring 

 them within the margins of experimental error. 12 



1 P. Panum, Virchow's Arch. 4. 419 (1851). 



2 K. Billow, Pfiugers Arch. f. d. ges. Physiol. 58. 207 (1894). 



3 B. Werigo, ibid. 48. 127 (1891). 



4 W. Kieseritzky, Die Gewinnung des Faserstoffs, Alkalialbuminats und Acidal- 

 bumins, Dissertation, Dorpat, 1882. 



5 A. Rosenberg, Dissertation, Dorpat, 1883. 



6 F. Goldschmidt, Sduren und Eiwess, Dissertation, Strassburg, 1898. 



J 0. v. Fiirth, Arch. f. experiment. Pathol. u. Pharmakol. 36. 231 (1895). 

 * F. N. Schulz, Zeitschr. /. physiol. Chem. 24. 449 (1898). 



9 J. Starke, Sitzungsber. d. Miinchener Gesellsch. f. Morphol. u. Physiol. 1897, p. 1. 



10 W. Erb, Zeitschr. /. Biol. 41.309 (1901). 



11 K. Spiro and W. Pemsel, Zeitschr. f. physiol. Chem. 26. 233 (1898). 



12 E. Salkowski, Zeitschr. f. Biol. 37. 401 (1899). 



