THE ALBUMINS PROPER 



357 



characters as solubility in salt solutions, but also in having the same 

 percentage-composition. 



2. Egg-Albumin 



Egg-albumin forms the chief constituent of that concentrated 

 albuminous solution known as egg-white or white of egg. The latter 

 contains, in addition to egg-albumin, also a globulin and a mucoid. 

 The mucoid has been investigated only recently by Morner 1 and 

 Zanetti, 2 and has been shown to be a distinct substance. For this 

 reason all the older and many of the more recent accounts of egg- 

 albumin do not deal with pure egg-albumin, but with mixtures of the 

 latter with various other albuminous substances. 3 Because of the ease 

 with which it may be obtained, egg-albumin has been more frequently 

 investigated than any other albumin. 



Hof meister 4 was the first to prepare an albumin in a crystalline 

 form from a half-saturated ammonium - sulphate solution, and this 

 albumin was egg-albumin. The method now used by Hopkins 5 is 

 described on p. 325. Instead of acetic acid, any other acid, such as 

 H 9 S0 4 , HC1, may be used, according to Schulz 6 and Hopkins. 7 



Analysis has yielded these values : 



This table shows that the analyses vary in quite an irregular 

 manner, as is specially noticeable in the sulphur-content, and the dis- 



1 C. T. Morner, Zeitschr. f. physiol. Ghem. 18. 525 (1893). 



2 C. U. Zanetti, Ann. Chim. di. e. Farmac. 12. (1897) (according to Maly's 

 Jahresbericht, 27. 31 (1897)). 



3 'L. Langstein, ' Uber die gerinnbaren Stoffe des Eierklars,' Hofmeister s Beitrage, 

 1. 83 (1901). (Here the older literature and many analyses.) 



4 F. Hofmeister, Zeitschr. f. physiol. Ghem. 14. 163 (1889). 



5 F. G. Hopkins, Journ. of Phys. 25. 306 (1900). 



6 F. N. Schulz, Zeitschr. f. physiol. Ghem. 29. 86 (1899). 



7 F. G. Hopkins, Journ. of Physiol. 25. 306 (1900). 



8 F. Hofmeister, Zeitschr. f. physiol. Ghem. 16. 187 (1891) ; 24. 159 (1897) ; 

 F. N. Schulz, ibid. 25. 1.6 (1898). 9 F. N. Schulz, ibid. 29. 86 (1899). 



10 St. Bondzynsky and L. Zoja, ibid. 19. 1 (1893). 



11 T. B. Osborne and F. G. Campbell, Journ. Americ. Ghem. Soc. 21. 477 (1899) ; 

 22. 422 (1900). 



