74 COLLOID CHEMISTRY OF THE PROTEINS 



1*5 



different protein salts, in which case variations in hydration 

 of the ions and of the neutral particles can have a combined 

 effect. The latter alternative can be regarded at once as 

 improbable, and, in analogy with typical metallic salts, we may 

 assume the identity of the albumin ions of the protein salts in 

 the same way that the same cations are found to be given by 

 the salts of a metal with different acids. Accurate electro- 

 metric measurements on albumin chloride show, however, that 

 a small portion of the acid combines with the protein in a manner 

 which appears to be molecular, both the ions taking part. 



Considerable differences in 

 the properties of the albumin 

 ions of different protein salts 

 may be caused by this portion 

 of the acid ; and that small 

 Oxalic Act 4 quantities of substances can 

 effect considerable changes 

 in the properties of the ions 

 of acid albumin is shown by 

 investigations of the com- 

 bination of acid albumin and 

 neutral salts (see later). The 

 molecular reaction of the 

 uncombined part of the acid 

 FIG. 17. Viscosity curves with various mu st also be considered, and 



it is probably no mere 



accident that the marked anomaly of sulphuric and trichlor- 

 acetic acids is coincident with their considerable power of 

 dehydration. As, however, the relations in ionisation of the 

 various protein salts, as determined by free anions, are at 

 the moment far from clear, a decision as to the origin of 

 the differing hydration of these salts must be sought in 

 other ways. In this respect the researches of Pauli and 

 Samec* on the optical rotation of protein salts provide 

 some useful suggestions. These authors found that even 

 in low concentrations both acids and bases give rise to an 

 increase in the optical rotation of albumin. The table and 

 * Biochem. Zeitsch., 1914, 59, 470. 



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