viii THE SALTING-OUT OF ALBUMINS 293 



Joachim, 1 have also fractionated globulin by means of potassium acetate 

 and ammonium sulphate. Oppenheimer, 2 working with serum-albumin, 

 and Cohnheim with the nucleo-proteid of natural gastric juice, have 

 further observed that these apparently uniform substances may be 

 broken up by means of ammonium sulphate into several fractions with 

 definite precipitation-limits, which latter remain constant even after 

 repeated reprecipitation, and that the fractions obtained in this way 

 do not differ from one another in any other respect. The question 

 naturally arises whether one is justified in regarding these fractions 

 really as distinct chemical individuals. Cohnheim believes that ad- 

 mixtures of any kind, that salt formation and similar factors, may 

 well produce these differences, for Fuld and Spiro have found that in 

 one of the globulin fractions, namely, in euglobulin, ferments, lime salts, 

 etc., are present. The author holds that the various fractions must 

 be considered to be definite individual substances, but as to whether 

 they occur naturally is quite a different question. If a sufficient 

 number of subfractions could be taken, then we ought to pass unin- 

 terruptedly from the mono- and di-amino-acids through the di- and 

 polypeptids to peptones, and so upwards. That, however, such 

 individual complexes as the hemi- and anti-, the thio-, and glyco- 

 groups exist seems to be beyond doubt. 



The salts which albumins form with acids and with bases may 

 also be salted out, as has been shown by Paal, 3 Cohnheim, 4 and Spiro 

 and Pemsel, 5 and this property may be used for determining the acid 

 and the basic capacity of albumins. The salts of albumin with acids 

 are indeed even more readily precipitated than are the albumins 

 themselves, for Pick and Zunz have found, if the reaction of an 

 albuminous solution be acid, that the precipitation-limits for ammonium 

 sulphate and zinc sulphate are always lowered, i.e. that precipitation 

 commences and terminates with a smaller percentage of these salts. 

 Salkowski 6 found similarly that all native albumins may be precipi- 

 tated from their solutions by means of sodium chloride if the reaction 

 be acid, while if the reaction be neutral the albumins are not 

 precipitated at all and the globulins only partially. Kiihne 7 has also 

 shown that sodium chloride precipitates albumoses much more 

 thoroughly if the reaction be acid. On the other hand, salts of 



1 E. Freund and J. Joachim, Zeitschr. f. physiol. Chem. 36. 407 (1902). 



2 C. Oppeiiheimer, Arch. f. (Anat. u.) Physiol. 1903, 201. 



3 C. Paal, Ber. d. deutsch. chem. Oes. 25. 1202 (1882) ; 27. 1827 (1894). 



4 0. Cohnheim, Zeitschr. /. Biolog. 33. 489 (1896). 



5 K. Spiro and W. Pemsel, Zeitschr. f. physiol. Chem. 26. 231 (1898). 



6 E. Salkowski, ZentralU. /. d. medizin. Wissenschaften, 1880. 



7 W. Kiihne, Zeitschr. f. Biol. 20. 11 (1884) ; 29. 1 (1892). 



