354 CHEMISTRY OF THE PROTEIDS CHAP. 



magnesium and sodium sulphates if these are used combinedly in 

 saturated solution, and also by sodium chloride 1 or magnesium 

 sulphate 2 if the reaction be acid. The precipitation-limits for 

 ammonium sulphate lie, according to Hofmeister, between 6'4 and 9 

 (see p. 292), and therefore very high; for this reason they are not 

 salted out by half -saturated solutions, and consequently half -satur- 

 ation is used for separating albumins from the globulins..with which 

 they are constantly found together. If albumin solutions have 

 an acid reaction, the precipitation -limits for ammonium sulphate are 

 lowered. 



The three albumins mentioned above have been prepared in a 

 crystalline form, and they differ in their crystalline character from 

 most of the other simple albuminous substances. The crystals have 

 already been discussed on p. 326, where it was pointed out that 

 they are probably not free albumins, but salt-like combinations, being, 

 for example, either sulphates or acetates. 



Albumins give all the colour- and precipitation-tests of albuminous 

 substances. 



1. Serum-Albumin 



It is found in varying amounts in the blood-serum of vertebrates, 3 

 and also in the lymph. It is therefore met with in all organs which 

 have not been freed thoroughly from blood and lymph. In inflamma- 

 tions of the kidney it passes into the urine, and is also found in patho- 

 logical transudations. Giirber 4 was the first to prepare it in a 

 crystalline form from the blood of the horse. According to Krieger 5 it 

 is best to employ ammonium sulphate and sulphuric acid (see p. 324), 

 for only sulphuric-acid solutions will give constant results with the 

 blood of the horse, while other acids fail occasionally according to 

 Giirber and Krieger. Giirber has also obtained crystals from the 

 plasma of the rabbit, while he and Schulz 6 failed in obtaining crystals 



1 P. Panum, Virchow's Archiv, 4. 419 (1851); E. Salkcnvski, Zentralbl.f. d. med. 

 Wissenschaften, 1880, p. 38 (Maly's Jahresber. 10. 16). 



2 Tolmatscheff, Hoppe-Seylers med.-chem. Untersuchungen, p. 272 (1867); 0. Ham- 

 marsten, Zeitschr. f. physiol. Chem. 8. 467 (1884); E. Jolmnnsson, ibid. 9. 310 

 (1885). 



3 O. Hammarsten, ibid. 8. 467 (1884) ; G. Salvioli, Archiv f. (Anat. n.) Physiol. 

 1881, p. 289 ; J. Joachim, Wiener kliniscJie Wochenschrift, 1902. No. 21 ; G. Meyer, 

 Medical Dissertation, Wiirzburg, 1896. 



4 A. Giirber, Wurzburger physiol.-medizin. Ges. 1894, p. 113 ; 1895, p. 26 ; 

 A. Michel, Wurzburger physiol.-medizin. Ges. 29. 117 (1895) (additional note by 

 Giirber, p. 139) ; G. Meyer, Medical Dissertation, Wiirzburg, 1896; E. Middeldorf, 

 Dissertation, Wiirzburg, 1898. 



5 H. T. Krieger, Dissertation, Strassburg, 1899. 



6 F. N. Schulz, Kristallisation von Eiweissstoffen, Jena, G. Fischer, 1901. 



