Amphoteric Colloids. I. Cii_emical Influence of the Hydrogen Ion Concentration

I t is often stated (Pauli, H6ber, and others) that both ions of a neutral salt affect the physical properties of an amphoteric electrolyte (ampholyte) simultaneously and in the opposite sense; so that the total result is the algebraic sum of the opposite action of the oppositely charged ions of the neutral salt. 1 The writer has beelz able to show by experiments on gelatin and on pig's bladder tha t this statement is not correct, but that apparently only one of the two ions of the neutral salt acts upon the ampholyte; namely, the one which has the opposite electric charge from that of the ampholyte. 2 The hydrogen ion concentration of the gelatin solution used by the writer was 10 -7 (or in S6rensen's logarithmic symbol pH = 7.0) and this gelatin reacted with neutral salts as if it were an anion capable of combining with the cation of a neutral salt. When, however, powdered gelatin is treated for some time with an acid, e.g. HC1, gelatin chloride (or hydrochloride) is formed, which is supposed to dissociate electrolytically into a positive gelatin ion and a negative chlorion. The writer found that when the supernatant