HE 



UNIVERSITY 



OF 



THE SALTING-OUT OF 



the additive effect of the two ions of a salt, and if this be so, Pauli 

 points out that the total effect produced by a mixture of several salts 

 in solution must be determined by the sum of all the ionic actions. 

 Pauli's modified view is given below. Acetates of the alkalies being 

 somewhat better coagulants than are the chlorides, one obtains a 

 greater effect in coagulating eggwhite by a mixture of sodium acetate 

 + potassium chloride than by an equivalent mixture of sodium acetate 

 + sodium chloride, as the dissociation of the sodium chloride by 

 saturating the solution partially with sodium-ions interferes with the 

 dissociation of the sodium acetate molecules. 



The fact that sodium sulphate does, while potassium sulphate does 

 not coagulate albumin, Hofmeister explained by assuming that in the 

 case of potash salts the solubility of these salts was not sufficient to 

 allow the solutions of requisite concentration being obtained. To test 

 this hypothesis Pauli employed two methods : He made a 20 per 

 cent potassium sulphate solution at 100 in a test tube, poured some 

 warm oil on the solution, and allowed it to cool in a big beaker till 

 the temperature had fallen to 50, then added, by means of a pipette, 

 some albumin solution, which, forming a layer between the oil and the 

 20 per cent potassium sulphate solution, produced a distinct turbidity 

 which was reversible on dilution. 



Potassium nitrate employed similarly could not be made to yield 

 a coagulum, and therefore recourse was had to the following method : 

 To a solution of a salt, capable of coagulating albumin, but of such 

 strength as to be just inefficient, potassium nitrate was added in the 

 crystalline form, when the mixture was found to coagulate. 



This experiment does not seem to the author to be at all conclusive, 

 for if the potash salt dissolves at all it can only do so at the expense 

 of the other salt in solution ; by attracting water molecules to itself it 

 must make the other salt-solution more concentrated, and the latter 

 being more concentrated may cause the coagulation of the albumin 

 quite irrespective of the potash salt. 



Do both ions of a salt cause coagulation, or is only one of the ions 

 concerned? and if so, what does .the other ion do? This question 

 suggested itself to Pauli because some electrolytes, such as the acetates, 

 nitrates, and chlorides of ammonium and magnesium, cause no coagu- 

 lation, notwithstanding the fact that they are very soluble ; and again 

 the fact that NH 4 coagulates in ammonium sulphate, but does not do 

 so in ammonium acetate, while at the same time the ace t-ion/ coagu- 

 lates in sodium acetate, while it does not coagulate in ammonium acetate, 

 makes it impossible to believe that both ions of a salt act in the same 

 sense, and therefore Pauli has come to the conclusion that in electro- 



