JACQUES LOEB 361 



solutions of the chloride of crystalline egg albumin showed a perfect 

 quantitative agreement with the theory. 



Collodion bags of about 50 cc. volume were filled with a solution 

 of 1 per cent crystalline egg albumin containing varying amounts of 

 0.1 N HCl, and the bags were put, as usual, into beakers containing 

 350 cc. of HCl solutions of different concentration but free from 

 albumin. The first two horizontal rows of Table II give the amount 

 of 0.1 N HCl in each solution. The experiments were carried out at a 

 temperature of 24°C. and after 22 hours the osmotic pressure, p. d., 

 and pH of inside (albumin) solution and pH of the outside solution 

 were measured, the p. d. with the Compton electrometer and the pH 

 with the hydrogen electrode. The albuminused was not isoelectric, but, 

 since it had been prepared after Sorensen's method, it was probably 

 partly ammonium albuminate, with a pH of near 6.0. The table 

 shows that the observed p. d. agree with the value 58 CpH inside 

 minus pH outside), i.e. the calculated p. d. (especially on the 

 acid side of the isoelectric point) ; that the p. d. is a minimum near 

 pH 4.7 of the albumin {i.e. near its isoelectric point which is at pH 

 4.8), and that the albumin is positively charged on the acid and nega- 

 tively charged on the alkaline side of the isoelectric point. This is 

 again in harmony with what we should expect on the basis of the 

 Donnan equilibrium. 



The next problem was to determine the influence of the addition 

 of a neutral salt to a solution of the chloride of crystalline egg albumin. 

 A 1 per cent solution of crystalline egg albumin containing 7 cc. of 

 0.1 N HCl in 100 cc. was made up in various concentrations of 

 NaCl. The collodion bags containing these albumin chloride-XaCl 

 mixtures were dipped into beakers containing 350 cc. of the same 

 concentration of NaCl as that of the albumin solution, and all made up 

 in n/1000 HCl. The experiment was carried out at 24°C. and the 

 measurements were m.ade after 22 hours. 



Table III gives the results which show again a good agreement 

 between the observed p. d. and the value 58 (pH inside minus pH 

 outside), our so called calculated p.d. 



We may, therefore, conclude that the p.d. of both gelatin solutions 

 and solutions of crystalline egg albumin separated by a collodion 

 membrane from a watery solution free from protein is accounted for 



