EXPERIMENT STATION BULLETINS. 



385 



TABLE I. 



With corallin as the indicator. 



TABLE II. 

 With purified litmus as the indicator. 



Number. 



PI.. 

 PII. 

 P III 

 RI. . 

 RII. 

 RIII 



Cubic 



centimeters 



dil. NH4 OH 



per 50 c c. 



sol. 



15.00 

 13.76 

 16.00 

 15.00 

 17.60 

 14.00 



Number. 



M I.. 

 M II. 

 M III 

 II.. 

 I II.. 

 I III. 



Cubic 



centimeters 



dil. NH4 OH 



per 50 c. c. 



sol. 



14.00 

 15.00 

 12.50 

 15.82 

 15.82 

 15.00 



An inspection of tliese results reveals the fact that the ofifieial method 

 gives extremely inconsistent results, even in the hands of one person. 

 In only one case was an exactly neutral solution secured. The variation 

 in the results obtained by one analyst using this method amounted to 

 seventy-four cubic centimeters of the dilute ammonium hydroxide solu- 

 tion per liter of the acid citrate solution. While this is the maximum 

 variation in the four sets of determinations given, it must, nevertheless 

 bo accepted as a possibility in actual practice. Such a condition is surely 

 anything but desirable and demands immediate attention. The other 

 method showed to much better advantage. Not only were the results 

 more consistent, but one-third of the trials actually gave neutral 

 solutions. 



These examples fairly illustrate the difficulty in making an exactly 

 neutral reagent by the methods most commonly in use and it is quite 

 possible that in many cases the character of the "neutral" ammonium 

 citrate solution varies more than in the cases cited and that considerable 

 error may be introduced into determinations in this way. It is evident 

 that not only is there a wide variation in the solutions made by different 

 individuals, but that even the same i>erson can rarely duplicate his own 

 results. 



It has long been realized that it was impossible to get consistent results 

 in neutralizing ammonium citrate solution by the official method, but 

 it has been assumed that the differences in. the acidity of th© solution 

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