THE GENERAL PHYSICAL PROPERTIES OF ALBUMINS 



271 



This table is exceedingly interesting, because it shows not only a 

 marked difference between the monovalent potassium and the divalent 

 barium, strontium and calcium, confirming Hans Schultze's l observation 

 that the relative coagulative power of mono-, di-, and trivalent metals 

 varies greatly, but also shows, according to the author's opinion, that 

 within the divalent metals the power of precipitating colloids increases 

 with the diminishing electro-affinity of the metals. 2 This fact is a 

 further support of the author's views on electrical dissociation and 

 solubility of salts, see pp. 255, 265, and 289. 



The fact that colloids may decompose such a 'neutral' salt as 

 barium chloride and induce its hydrolysis shows that colloids must 

 be chemically active, i.e. that they must be electrolytes or hydrolytes 

 (see pp. 254-256). The first observer to point out that 'inert' 

 substances may decompose neutral salts in the presence of water, and 

 that they may join either with the acid or basic radical set free, was 

 v. Bemmelen, 3 who investigated such porous substances as animal 

 charcoal, silicic acid, and coagulated colloids. 



CHANGES INDUCED IN COLLOIDS BY PHYSICAL AND 

 CHEMICAL MEANS 



The author's view that colloids are electrolytes and capable of 

 reacting with H and OH' ions was expressed by him in 1902 4 in the 

 following way : 



" (1) Direct union between an acid and the colloid : 



Colloid + HC1 + water = (colloid + H) + Cl + H 2 0. 



[In this case the ion (colloid + H) is a complex ion, comparable to 

 the ion (PtCl 6 )" of the so-called platinum chloride H 2 PtCl 6 .] 



1 Hans Schultze, " Schwefelarsen in wasseriger Losung," Journ. f.prakt. Chem. 25. 

 431 (1882), and 26. 320 (1883). 



2 Mann, Physiological Histology, p. 14. A table of electro-affinities copied from 

 Abegg and Herz is given on p. 313 of this book. 



3 v. Bemmelen, Zeit. f. anorg. Chem. 23. 321 (1900). 



4 Mann, Physiological Histology, p. 48. 



