STUDIES ON THE REGULATION OF OSMOTIC 

 PRESSURE. 



II. The Effect of Increasing Concentrations of Albumin on 

 THE Conductivity of a Sodium Chloride Solution. 



By WALTER W. PALMER, DANA W. ATCHLEY, and ROBERT F. LOEB. 



{From the Department of Medicine of the College of Physicians and Surgeons 

 of Columbia University, and the Presbyterian Hospital, New York.) 



(Received for publication, March 23, 1922.) 



introduction. 



It has been shown^ that the addition of gelatin in increasing con- 

 centrations to a 0.6 per cent sodium chloride solution afifects the con- 

 ductivity in two ways, depending on the hydrogen ion concentration. 

 At pH 3.3 the conductivity increases with each added increment of 

 gelatin, whereas at pH 5.1 and 7.4 the conductivity decreases as the 

 percentage of gelatin increases. It was suggested that the addition 

 of gelatin to a solution of sodium chloride has two opposite effects: 



(1) to increase the conductivity by the addition of ionized gelatin, and 



(2) to decrease the conductivity by the mechanical interference of 

 the undissociated gelatin molecules. The relative value of these 

 two influences seemed to depend on the degree of ionization of the 

 gelatin, which in turn is dependent upon the hydrogen ion concentra- 

 tion. The experimental results indicated that at pH 3.3 the first effect 

 obtained, while at pH 7.4 and 5.1 the second effect was pre- 

 dominant. 



This paper presents similar experiments with another protein; 

 viz., egg albumin. A preliminary determination of the conductivities 

 of pure egg albumin solutions varying in concentrations from 0.8 

 to 8.7 per cent was carried out as in the case of gelatin. 



I Palmer, W. \Y., .\tchlcy, D. W., and Loeb, R. F., /. Gen. Physiol., 1920-21, 

 iii, 801. 



585 



