JACQUES LOEB 



831 



drogen ion concentration should have a similar influence on the 

 viscosity of solutions of simple amino-acids, like glycocoll and alanine, 

 as it has on the viscosity of gelatin solution. 5 per cent solutions of 

 glycocoll and alanine were brought to different pH, from 5.0 to 

 2.0 and below, by the addition of HCl. The variation of the pH 

 of 5 per cent solutions of these two amino-acids between the limits 

 of 5.0 and 1.16 had no measurable influence on the viscosity of the 

 solution. This cast a serious doubt on the assumption that the varia- 

 tions in the curve of the viscosity of gelatin, as expressed in Fig. 1, 

 were caused by variations in the hydration of the individual gelatin 

 ions.^^ 



.o § 1.5 

 <3 £0 j4 





1.2 



8 Z5 



^a 1.1 



> «3 



1.0 



pH 0.8 1.0 1.2 1.4 1.6 1.8 2.0 22 24 2.6 2.8 30 3.2 34 3.6 3.8 40 42 44 



Fig. 2. Showing that solutions of crystalline egg albumin have a low viscosity 

 in comparison with gelatin solutions, and that the pH has little influence on the 

 viscosity of solutions of crystalline egg albumin at pH over 1.0 and at ordinary 

 temperature. 



This doubt was increased by experiments on the influence of pH 

 on the viscosity of crystalline egg albumin which gave also a practi- 

 cally negative result. Fig. 2 gives such an experiment with 3 per 

 cent originally isoelectric albumin brought to different pH through 

 the addition of HCl. The ordinates are the viscosity ratios of al- 

 bumin solution over water, drawn on a larger scale than those in 

 Fig. 1, and the abscissae are the pH of the solution. It is obvious that 

 the pH has only a very slight if any influence on the viscosity 

 of solutions of crystalline egg albumin between pH 4.6 and pH 1.0, 

 With a further lowering of pH the viscosity suddenly rises, a fact 

 to which we shall return later. It is also obvious that the viscosity 



^ These experiments were carried out by Dr. Elizabeth Brakeley. 



