544 ANTAGONISTIC ACTION OF ANIONS 



The method employed to measure the effects of the salts is the same 

 as that mentioned in a former paper.^ 



The salts used were the purest obtainable. The distilled water 

 was not toxic to delicate test objects. The solutions had a pH value 

 of 7 ± 0.5 as measured by phenolsulfonephthalein and buffers which 

 had previously been checked by the gas chain method. The experi- 

 ments were conducted at a temperature of 19 ± 2°C. 



This paper deals with the eflects of sodium acetate and sodium 

 sulfate. Solutions of these salts were made of the same electrical 

 conductivity as a slightly diluted sea water (about 1.1 m for sodium 

 acetate and about 0.36 m for sodium sulfate) and the resistance of 

 the tissue in solutions of the pure salts and in mixtures was measured 

 after 5 minutes and thereafter at intervals of 20 minutes. 



Fig. 1 shows the results. Each curve represents the average of 

 ten experiments. The probable error of the mean (as computed by 

 Peter's formula) is under 5 per cent in all cases. 



On placing tissue in the pure acetate we observe that at the end of 

 If hours the resistance has fallen to about 40 per cent of the original 

 and in the pure sulfate it has fallen to about 25 per cent of the origi- 

 nal, while in the mixture composed of equal volumes of the solution 

 of each salt the resistance has fallen only to about 60 per cent. If 

 no antagonism were present, the resistance of the mixture should 

 drop to about 35 per cent (additive effect). 



Fig. 2 shows the antagonism curves after various intervals using 

 resistance for ordinates and salt proportions as abscissa?. Here the 

 antagonism is clearly evident. 



In view of the importance of the subject, further investigation seems 

 desirable. The case here described is so striking as to warrant the 

 conclusion that any theory of the antagonistic action of salts must 

 take account of anions as well as of cations. 



^Raber, O. L., Proc. Nat. Acad. Sc, 1917, iii, 682. 



