STUDIES ON THE REGULATION OF OSMOTIC PRESSURE. 



I. The Effect of Increasing Concentrations of Gelatin on 

 THE Conductivity of a Sodium Chloride Solution. 



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



{From the Chemical Division of the Medical Clinic of the Johns Hopkins University 



and Hospital.) 



(Received for publication, May 20, 192 L) 

 INTR,ODUCTION. 



In a study of the factors influencing the regulation of osmotic 

 pressure of the body fluids, the physical properties have been deter- 

 mined in a series of blood sera from normal and pathological indi- 

 viduals. In the case of some patients, there was found a strikingly 

 low percentage of serum protein. The conductivity of the salts in 

 blood with a low percentage of serum protein was high compared with 

 the conductivity of the same salts in normal blood. It occurred to 

 us that possibly the protein molecules offer mechanical interference 

 to the passage of the current through the solution, hence, when the 

 protein content of the solution is diminished the observed conductivity 

 wiU increase without a corresponding increase in the concentration of 

 ions present. It was to throw light upon this hypothesis that a study 

 of the relation between conductivity and concentration of gelatin was 

 undertaken. 



In 1898 Bugarszky and Tangl^ pointed out that, of the non-con- 

 ducting substances in the serum, protein is the only one present in 

 amounts sufiicient to affect the electrical conductivity. These 

 authors derived a formula by the addition of serum protein in varying 

 quantities to a salt solution of constant conductivity. The serum 

 protein was obtained by dialyzing blood serum for two months and 

 concentrating under reduced pressure. The hydrogen ion concen- 

 tration was not controlled in their experiments. 



^Bugarszky, St., and Tangl, F., Arch. ges. Physiol., 1898, Ixxii, 531. 



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