JACQUES LOEB 767 



other bivalent and monovalent ions act differently, since the 

 valency is not the only variable determining the combining action.^ 



These results are in entire agreement with the experiments 

 published in a preceding paper^ showing that only salts with 

 trivalent and tetravalent ions can produce a membrane potential 

 on isoelectric gelatin while Na, Ca, Ba, and SO4 have no such 

 effect. 



When crystalline egg albumin is dissolved in a solution with 

 little water and much alcohol, salts have not the same influence on 

 the stability of the solution that they have in an aqueous solution. 

 This is due to the difference in the nature of the solvent, since the 

 influence of salts on the stability of such alcoholic solutions of 

 crystalline egg albumin is similar to the influence of salts on the 

 stability of solutions of gelatin in a solution with much alcohol and 

 little water. The stability of isoelectric gelatin in a mixture with 

 little water and much alcohol is increased not only by salts with 

 trivalent and tetravalent ions but also by salts with bivalent ions, 

 such as MgClo, CaClj, SrCl2, BaCl2, and Na2S04, while salts like 

 MgS04, LiCl, NaCl, or KCl have no such effect. The clearing 

 effect of Ba was considerably greater than that of Mg. We know 

 too little about the p.d. and solubility in alcoholic solutions and for 

 this reason the publication and discussion of these results may be 

 postponed. 



SUMMARY AND CONCLUSION. 



1. While crystalline egg albumin is highly soluble in water at 

 low temperature at the pH of its isoelectric point, it is coagulated 

 by heating. It has long been known that this coagulation can 

 be prevented by adding either acid or alkali, whereby the protein 

 is ionized. 



2. It is shown in this paper that salts with trivalent or tetra- 

 valent ions, e.g. LaCl.i or Xa4Fe(CN)G. are also able to prevent 

 the heat coagulation of albumin at the isoelectric point {i.e. pH 4.8), 

 while salts with a divalent ion, e.g. CaClo, BaCla, Na2S04, or salts 

 like XaCI, have no such effect. 



5 Michaelis, L.. and Rona. P., Biochcm Z.. 1919, xciv. 225. 



