1912] Lipman-SJiarp: Phcnoldisulphonic Acid Method 27 



nature of the action of the salts in question. The results of 

 these experiments, which will be given below, make entirely clear 

 what seemed at first quite puzzling. 



In further general discussion of the tables above given, it 

 must be added that the decreases in the nitrate content of the 

 solutions tested as induced by the presence of salts never oc- 

 curred in accordance with any definite law, the losses at times 

 being greater with smaller amounts of salts than w4th larger 

 amounts, the amounts of nitrates being constant. On the other 

 hand, with a given amount of nitrates not exceeding one-tenth 

 of a milligram the salts seemed always to induce larger per- 

 centage losses than they did in the case of the larger amounts of 

 nitrates. Our results not only give good opportunity for a com- 

 parison of the effects of varying quantities of salts on the same 

 nitrate content, but point out all the relationships between the 

 salts and nitrates where first the former, then the latter, and 

 finally both, are varied. There are two other points, also, which 

 they would not seem to confirm ; indeed they give entirely different 

 evidence on these than was obtained by other investigators. The 

 first is that small amounts of NaCl do not induce losses of 

 nitrates, as claimed by Stewart and Greaves, and Table I indi- 

 cates that amounts of NaCl below .1 milligram do not occasion 

 any losses. The other point of difference between our results and 

 those of the others mentioned is that NaoCOg does not decrease the 

 amounts of nitrates, no matter to what extent it is used, as shown 

 in Table III. This is in entire disagreement with the results of 

 Gill and Chamot and his coworkers, who claimed that Na2C03 

 and other carbonates induced losses of nitrates, in the determina- 

 tion outlined. It must also be added here that the effects of 

 Na.SO^ as given in Table II constitute the first published results, 

 so far as we are aware, on the effects of Glauber salt on the 

 nitrate determination, and they have indeed been indirectly re- 

 sponsible for the discovery of one or two other points of interest 

 which will be discussed below. 



The results above given indicate the effects of each of the 

 salts taken singly on the nitrate determination. To make the 

 data more complete it was thought desirable to test various mix- 

 tures of the same salts and note their effects. Table IV gives 

 the results obtained. 



