viii THE SALTING-OUT OF ALBUMINS 289 



that an analogous change may very well be produced in egg-white, 

 and that for this reason in the above table the iodides and thiocyanates 

 have apparently so strong an inhibiting action on all kat-ions. The 

 formation of double salts has also not been taken into account, nor has 

 sufficient attention been paid to the amphoteric character of the 

 albumin. Posternak's researches (see p. 282) seem to have escaped 

 Pauli also. 



That, however, so-called ' neutral ' salts are in reality not neutral, 

 but are composed of ions in which either the negative or the positive 

 electro-affinity preponderates, has been explained on p. 265, and Pauli's 

 observations seem to bear out the author's views, and there cannot be 

 any doubt that the preponderating positive or negative electro-affinity 

 is the factor which makes the dehydration of the albumin molecule 

 possible, and thus leads to its coagulation. The author is therefore of 

 the opinion that salting-out with neutral salts is in the last instance 

 simply a question of dehydration according to the old view of Virchow 

 and Hofmeister, and that the albumin molecules, when they become 

 dehydrated, behave as would other salts, by losing all power of 

 dissociating either electrolytically or hydrolytically. 



The salting-out process has become of the very greatest importance 

 in studying the chemistry of albuminous substances, as it does not lead 

 to the denaturalisation of albumins. Another great advantage of 

 salting-out is that the individual albumins may be separated from one 

 another to a much greater extent than by any other precipitation- 

 method, and salting-out has therefore rendered the greatest service in 

 the preparation of pure albumins. 



Salting-out with sodium chloride and magnesium sulphate has been 

 investigated by Tolmatscheff, 1 Hammarsten, 2 Burkhardt, 3 and Halli- 

 burton. 4 Ammonium sulphate, the most efficient of all the salts, was 

 introduced by Heynsius 5 and extensively used by Kiihne, 6 who also 



1 Tolmatscheff, 'The Analysis of Milk,' Hoppe-Seyler's Medizin.-chem. Untersu- 

 chungen, p. 272 (1867). 



2 0. Hammarsten, ' Paraglobulin, ' Pfiilger' s Arch. f. d. ges. Physiol. 17. 413 (1878) ; 

 K. V. Starke, ' Abstract of the Swedish Original by Hammarsten ' in Maly's Jahresber. 

 /. Tierchemie, 11. 17 (1881). 



3 Burkhardt, Arch. f. exp. Path. u. Pharm. 16. 322 (1882). 



4 W. D. Halliburton, 'Muscle-Plasma,' Journ. of Physiol. 8. 133 (1887); and 

 'Proteids of Milk,' ibid. 11. 448 (1890). 



5 A. Heynsius, Pflugers Archiv f. d. ges. Physiol. 34. 330 (1884). 



6 W. Kiihne, Verh. des Heidelberger naturh.-mediz. Vereins, N.F. 3. 286 (1885) ; 

 W. Kiihne and K. H. Chittenden, Zeitschr. f. Biol. 20. 11 (1884) ; 22. 423 (1886) ; 

 S. Wenz, 22. 1 (1886). 



U 



