vi THE REACTION OF ALBUMINS 223 



Pemsel, is not more than 1178. The numbers given by Billow 1 for 

 the chlorides, and by Chittenden and Whitehouse 2 for the salts of the 

 heavy metals of egg-white, differ more widely. 



These salts differ from those previously described in possessing 

 an approximately neutral reaction, a fact which also holds good for 

 the casein salts, although casein is distinctly acid in its free state. 

 Besides the above-mentioned salts, the authors just named describe 

 other salts containing a higher percentage of metal and possessing 

 a distinctly alkaline reaction. In dealing with these salts we have 

 to keep in mind two possibilities : the small amounts of acid or of 

 base which are found represent either a last remnant which has 

 escaped hydrolysis, in which case the relative constancy of the values 

 obtained has to be explained on the ground that the solubility of 

 these salts remains fairly constant under the conditions of experi- 

 mentation, or there are differences between the acid or the basic groups 

 in the albumin-molecule, some giving rise to stable salts, while others 

 undergo extensive hydrolysis. It has already been mentioned that 

 it is possible for such differences to exist amongst amino-acids, even if 

 the presence of sulpho-radicals is left out of account. 



Both amino-acids and albumins may be deprived of their basicity 

 by means of formaldehyde, there being formed, according to Blum, 3 

 Benedicenti, 4 Schiff, 5 and Schwarz, 6 methylene-albumins with markedly 

 acid properties. 



Albumins and all their derivatives resembling albumin possess, 

 without exception, the power of uniting with acids and with bases as 

 kations and as anions ; but as in the case of the amino-acids so here 

 either the basic or the acid character may predominate. 



The albumins proper seem to possess a neutral, if anything a slightly 

 alkaline, reaction. 



Nucleo- albumins and mucins are strongly acid, as they displace 

 carbonic acid from carbonates and as they redden litmus paper ; they 

 are precipitated by acids and dissolved by alkalies. The same holds 

 good, although to a lesser degree, for the nucleo-proteids, with their 

 nucleic acid radical, and holds good also for the globulins. 



Histones, on the other hand, are basic substances which are pre- 

 cipitated by alkalies and dissolved by acids. Still more strongly basic 



1 K. Billow, Pftiigers Arch.f. d. ges. PhysioL 58. 207 (1894). 



2 R. H. Chittenden and H. H. Whitehouse, Holy's Jahresber. f. Tierchem. 17. 11 

 (1887). 



3 F. Blum, Zeitschr. f. physiol. Chem. 22. 127 (1896). 



4 A. Benedicenti, Arch.f. (Anat. u.} PhysioL 1897, p. 217. 



5 H. Schiff, Liebig's Annalen, 319. 287 (1901). 



6 L. Schwarz, Zeitschr. f. physiol. Chem. 31. 460 (1900). 



