THERAPEUTIC STUDIES ON IONS. 75 



protein in which the precipitating power of the cations 

 exceeds the inhibiting effects of the anions. Let us 

 study the above table with this idea in mind. The table 

 shows along the horizontal the metallic ions arranged 

 in the order of their precipitating power, along the vertical 

 the anions arranged in the order of their inhibiting effect. 

 It is now at once intelligible why sodium nitrate, with 

 its powerful precipitating sodium ion, coagulates protein, 

 while the weaker precipitants, K, NH 4 , and Mg ions, 

 are overcome in their effects by the antagonistic NOs 

 ion. Only the lithium salt of the bromides precipitates, 

 and so we might go on. 



The table discloses yet other facts. If it is true that 

 the effect of salts upon proteins is determined through 

 the antagonistic properties of their ions, then there must 

 exist not only salts which precipitate protein or are in- 

 different, but also such as prevent precipitation or dis. 

 solve already existing precipitates. Observation has con- 

 firmed this important conclusion. When it has been 

 determined experimentally that a certain salt behaves 

 indifferently toward protein, then it will be found that 

 all other salts found to the right and above the point 

 occupied by this salt in the table will have precipitating 

 properties, while salts found to the left and below this 

 point will inhibit protein precipitation. The fact that 

 it has been the protein-precipitating salts which have 

 until now chiefly held the attention of investigators has. 

 prevented the recognition of this conspicuous phenom- 

 enon. 



An experiment will best illustrate what has been said. 

 Each of this series of test-tubes contains the same amount 

 of solvent, and neutral potassium tartrate in sufficient 



