JACQUES LOEB 765 



albumin. If other ions, like La, Ca, Na, SO4, have such an effect 

 on aqueous solutions of isoelectric albumin, it should show itself 

 in the prevention of heat coagulation and in the optical appearance 

 of the albumin solution after heating. 



The experimental procedure was as follows: 7 cc. of water of 

 pH 4.8 (this pH being the isoelectric point of crystalline egg al- 

 bumin) were added to 2 cc. of 1 per cent solution of isoelectric 

 crystalline egg albumin (of course, also of pH 4.8) and then 1 cc. 

 of a salt solution containing different salts of different concentra- 

 tion, but always of pH 4.8, was added. The test-tubes containing 

 the 10 cc. of the mixtures were put into boiling water until the 

 liquid in the test-tubes reached a temperature of 90°C. and then 

 the test-tubes were taken out of the water bath and allowed to cool 

 at room temperature. Table II gives the appearance of the 

 various mixtures after standing over night. 



These experiments show first that the heat coagulation of iso- 

 electric solutions of crystalline egg albumin is prevented by the 

 addition of low concentrations of LaCls or Na4Fe(CN)6 of pH 4.8. 

 The concentration of LaCls sufficient for this purpose was m/5,000 

 and that of Na4Fe(CN)6 about the same. Hence these two salts 

 acted on the heat coagulation of isoelectric egg albumin like acids 

 or alkali respectively. Moreover, it is obvious from Table II 

 that at first the size of the micellae formed diminishes with increas- 

 ing concentration of LaCls ions until the molecular concentration 

 of LaCls is about m/160. With a further increase of concentration 

 of salt the size of the micellae increases again (at 3 m/80) owing to 

 the fact that the p.d. is depressed by the CI ions; and at m/20 

 LaCls this depressing action of the CI ions on the p.d. is sufficient 

 to permit again the heat coagulation of the albumin. In the case 

 of Na4Fe(CN)6 the solution ceases to be clear when the concentra- 

 tion becomes 6m/80; in this case the depressing action of the 

 Na ions on the p.d. of the negatively charged micelL-e is so great 

 that the micelkc begin to coalesce again. 



None of the other salts tried, CaCla, BaCl2, NaCl, or Xa2S04, 

 is able to prevent heat coagulation of isoelectric egg albumin in 

 an aqueous solution of pH 4.8. It is, of course, possible that certain 



