I 



58 COLLOID CHEMISTRY OF THE PROTEINS 



hence its constitution is analogous to that of ammonium 

 chloride." 



Bugarsky and Liebermann attribute to the albuminium 

 chloride a smaller dissociation than that of ammonium chloride, 

 and hence, as soon as a sufficient excess of free hydrochloric 

 acid is present, as is the case with a lower albumin content, the 

 compound is but little ionised. When, however, much albumin 

 is in solution, and the acid almost completely combined with 

 it, the dissociation into Cl' ions, which in lower concentration 

 is suppressed, comes into play, giving thus many more Cl' 

 than H* ions. This thoroughly plausible conclusion has been 

 accepted by most authorities, although it is based solely on 

 the single experiment quoted above. Indeed, it rests entirely 

 on the difference in combination of H- ions and Cl'ions 

 observed once only at an albumin concentration of 6-4 gm. 

 This view was controverted by T. B. Robertson,* who pointed 

 out the quite inadequate experimental evidence for it, and 

 pronounced the single experiment relied on by Bugarsky and 

 Liebermann as doubtful. Robertson, on his part, supposes 

 that when albumin combines with acids, complete combination 

 with both ions always ensues ; and, as the conductivities of 

 such acid protein mixtures assume such high values, that not 

 merely the small balance of free acid but also the acid albumin 

 must contribute to it. Robertson therefore assumes that fresh 

 positive and negative protein ions are formed, of which the 

 former should contain the H' ion and the latter the Cr ion.f 



This hypothesis, which is put forward as quite general, we 

 have proved to be certainly inapplicable to the combination 

 of albumin or glutin with acids. It is, in the first instance, 

 contrary to the fundamental fact that cataphoresis experiments 



* " The Physical Chemistry of the Proteins." Longman. 1918. 

 | According to Robertson, albumin reacts with HC1 by the operation 

 of the peptide linkage : 



CO NH > C(OH) = N 



Thus 



H 



. . . C(OH) =--- N ... 4- HC1 > . . . COH ++ . . . + N" . . . 



Cl 



