C. F. Roberts — Estimation of Chlorates and Nitrates. 235 



It will be seen that the results reckoned from the iodine are 

 in general larger than those obtained by either of the other 

 methods. This is what might be expected on account of the 

 difficulty of completely removing air from the apparatus and 

 solutions employed, and such air would naturally cause an 

 excess of iodine. In (4) especially it will be noticed that we 

 have an abnormally large amount of iodine set free, and this 

 may undoubtedly be attributed to air, since it was observed 

 that the current of carbon dioxide was rather sluggish at the 

 time of that experiment. 



The average of the above-recorded experiments would give 

 as the value of fifteen cubic centimeters, from the method of 

 Kinnicutt and !Nef, '0697 grams, from the nitric oxide, -0699 

 grams, and from the iodine *0711 grams. If we assume that 

 the mean weight per fifteen cubic centimeters is represented 

 by the average of these three modes of determination, we 

 obtain 0*0702 grams, and that is the number which is used in 

 the following determinations to represent the weight of sodium 

 nitrite in fifteen cubic centimeters of the solution. The fol- 

 lowing experiments were made in the same way as the preced- 

 ing, except that potassium nitrate was introduced in the dry 

 state before the air was driven out of the apparatus, and the 

 results were calculated from the formula given above. 





W 



eights taken. 



Weights found. 



Difference. 



(1) 



Sodium nitrite 



0-0702 



0-0718 



0-0016 



Potassium nitrate 



o-iooo 



o-iooo 



o-oooo 



(2) 



Sodium nitrite 



0-0702 



0-0712 



0-0012 



Potassium nitrate 



o-iooo 



0-0999 



o-oooi 



(3) 



Sodium nitrite 



0-0702 



0-0710 



0-0008 



Potassium nitrate 



o-iooo 



0-1004 



0-0004 



M 



Sodium nitrite 



0-0702 



0-0698 



0-0004 



Potassium nitrate 



o-iooo 



0-1012 



0-0012 



(5) 



Sodium nitrite 



0-0468 



0-0453 



0-0013 



Potassium nitrate 



o-iooo 



0-0994 



0-0006 



(6) 



Sodium nitrite 



0-0468 



0-0444 



0-0024 



Potassium nitrate 



0-0500 



0-0513 



0-0013 



Though the process is one in which the most perfect accu- 

 racy cannot be assured in all cases, the above results show that 

 it is capable of giving fairly accurate results, sufficient for 

 many analytical purposes. It seems to be especially well 

 adapted to the estimation of the commercial alkali nitrites, the 

 whole determination being made on one portion and by one 

 operation, instead of on two different portions. 



