Abstract
From the dilution law, or from the equations for the equilibrium of an amphoteric electrolyte in the presence of non-amphoteric electrolytes, it can be shown that in the case of a protein in which the acid function considerably exceeds the basic function (as, for example, in the case of casein), an equation can be obtained connecting the observed conductivity of a neutral solution of the protein compound of a base with the dilution of the solution. This equation involves two constants, the one being the dissociaation-constant of the protein salt of the base and the other the sum of the specific velocities of the anions and cations present.
If a solution of a hydroxide of an alkali or alkaline earth or ammonia be shaken up with casein until no more casein goes into solution, the solution (as I have previously shown) is, after filtration, neutral in reaction and is a solution of the neutral caseinate of the base, containing an amount of the base equivalent to 2.4 per cent. CaO.
Since these solutions are neutral, if no cotnplex ions are formed, the conductivity will be entirely due to the cations of the base employed and to the casein anions. The sum of the ionic velocities obtained from the above-mentioned equation will therefore be greater than the specific velocity of the cation of the base by the specific velocity of the casein anion. In the case of the neutral caseinate of sodium the sum of the ionic velocities was found to be slightly greater than the velocity of the Na ion, indicating a specific velocity of 2.6 × 10-5 cm. per sec. for the casein anion at 25°. In the case of ammonium caseinate, however, the sum of the ionic velocities was found to be considerably less than the specific velocity of the ammonium ion.
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