vni THE SALTING-OUT OF ALBUMINS 291 



Why salts follow one another in this order we do not know at 

 present, but below an attempt will be made to account theoretically 

 for some of the facts. 



A number of salts which are good precipitants, such as sodium 

 chloride and magnesium sulphate, possess the property of precipitating 

 certain albuminous compounds not only in saturated but also in 

 partially saturated solutions. This property was first discovered by 

 Hammarsten 1 and made use of by Hofmeister's pupil Lewith, 2 

 and by Halliburton. 3 The systematic employment of fractional 

 precipitation by means of ammonium sulphate and zinc sulphate led 

 in the hands of Hofmeister and his pupils 4 to the crystallisation of 

 albumins ; the preparation of many albumins in a pure form, and 

 to much light being shed on the constitution of albumoses. 



It has been found that each albumin begins to be precipitated 

 whenever the concentration of the salt has reached a certain point, and 

 that at a definite higher concentration the precipitation comes to an end 

 because practically the whole of the albumin has been thrown down. 

 Hofmeister states that the precipitation-limits for ammonium sulphate 

 " are quite as characteristic for an albumin as is the solubility of a 

 crystalline substance." The special precautions which are necessary for 

 completely separating different albuminous fractions from one another 

 are given on p. 184. 



Kiihne has observed that the concentration of an albumin must 

 not be altered to any extent when making salting-out experiments, 

 and this observation has been amply confirmed by Hofmeister, Kauder, 

 Pick, and Zunz. It is therefore best to proceed as follows : Certain 

 definite amounts of an albumin solution are taken ; to these amounts 



1 0. Hammarsten, ' Fibrin ogen,' Pfliigers Arch. f. d. ges. Physiol. 19. 563 (1879); 

 22. 431 (1880). 2 J. Lewith, Arch.f. experim. Pathol. u. Pharmak. 24. 1 (1887). 



3 W. D. Halliburton, 'Proteids of Kidney and Liver-Cells,' Journ. of Physiol. 13- 

 806 (1892). 



4 G. Kauder, 'Albumins of the Blood-Serum,' Schmiedberg 's Arch. f. experiment. 

 Pathol. u. Pharmakol. 2O. 411 (1886) ; J. Pohl, ibid. 20. 426 (1886) ; F. Hof- 

 meister, 'Crystalline Egg- Albumin,' Zeitschr. /. physiol. Chem. 14. 165 (1889) ; E. P. 

 Pick, ibid. 24. 246 (1897) ; F. Urnber, ibid. 25.258 (1898) ; Fr. Alexander, 'Caseine- 

 Albumoses,' ibid. 25. 411 (1898); R. Bernert, 'Oxidation with Potassium Perman- 

 ganate,' ibid. 26. 272 (1898); E. Zunz, 'Zinc Sulphate,' ibid. 27. 219 (1899); E. 

 Zunz, 'Peptic Dissociation of Albumin,' ibid. 28. 132 (1899) ; E. P. Pick, ibid. 28. 

 219 (1899) ; W. Keye, Fibrinogen, Dissertation, Strassburg, 1898 ; H. Krieger, 

 Crystalline Albumins, Dissertation, Strassburg, 1899 ; F. Goldschmidt, Albumin 

 and Acids, Dissertation, Strassburg, 1898; A. Magnus-Levy, ' Bence- Jones' Albumin,' 

 Zeitschr. f. physiol. Chem. 30. 200 (1900) ; 0. Maas, ' Dissociation with Alkalies,' ibid. 



30. 61 (1900) ; L. Langstein, ' Ova- Albumin,' ibid. 31. 49 (1900) ; E. Fuld and K. Spiro, 

 'Serum-Globulin,' ibid. 31. 132 (1900) ; E. P. Pick and K. Spiro, 'Coagulation,' ibid. 



31. 251 (1900) ; E. P. Pick, ' Deutero- Albumoses, ' Hofmeister s Beitrage, 2. 481 (1902) ; 

 0. Porges and K. Spiro, ibid. 3. 277 (1902). 



