CHAPTER VI 



THE SALTS OF ALBUMINS 



I. THEORETICAL CONSIDERATIONS 



THE behaviour of amino-acids under different conditions is to the 

 biologist of very special interest, and therefore the physico-chemical 

 aspect has been gone into somewhat more fully by the author. 



Amino-acids in many respects resemble the pyrons, 1 for both 

 possess the power of forming additive compounds with acids and with 

 bases. Strecker 2 seems to have been the first to advance the view 

 that amino-acids fix metals by their CO . OH radical, while they 

 bind acids by the NH 2 -group, and the same conclusion has been 

 arrived at by Bredig, 3 Winkelblech, 4 and Walker, 5 who have studied 

 amino-acids in the light of physical chemistry. Bredig uses the term 

 'amphoteric electrolyte' for any substance 'which may split off, or 

 unite with, H and OH' ions,' 6 or, in other words, any substance 

 which can play the part of an acid towards a base or that of a base 

 towards an acid. According to this definition, water is an amphoteric 

 electrolyte because its hydrogen-atom H and its hydroxyl-radical OH 

 may be converted into the chemically active ions H and OH' when- 

 ever water comes into contact with certain salts, as will be shown 

 more fully later. Alcohols (C n H 2n+1 )OH are also amphoteric electro- 

 lytes. Thus (C n H 2n+1 )OH can unite with sodium according to the 



1 R. Willstatter and R. Pummerer, Ber. d. deutsch. diem. Ges. 37. 3740 (1904) ; 

 and J. N. Collie, Journ. Chem. Soc. 1904, p. 971. 



2 F. A. Strecker, Ann. d. Chem. 148. 87 (1886). 



3 G. Bredig, Zeitschr.f. Elektrochemie, 1899, No. 2. 



4 K. Winkelblech, Vber amphotere Elektrolyte und innere Salze, Leipziger Disserta- 

 tion, 1901 ; Zeitschr.f. physikal. Chem. 36. 546 (1901). 



6 James Walker, Zeitschr.f. physik. Chem. 49. 82 (1904). 



6 According to Ostwald's plan, a dot placed behind an atom or group of atoms 

 signifies a positive electrical load, while a stroke stands for a negative load. In this 

 book the dot has been replaced by a circle, thus H stands for positive hydrogen-ion and 

 d' stands for negative chlorine-ion. 



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