VOLUMETRIC METHOD OF GANTTER 421 



taken which will give not less than 30 and not more than 140 

 cubic centimeters of nitric oxid. 



The quantities of the different compounds of nitric acid cor- 

 responding to the number of cubic centimeters of nitric oxid, 

 measured under standard conditions, are shown in the following 

 table : 



Corresponding to 



Cubic centimeters Weight in 

 of NO. milligrams. 



* 1-343 



2 2.682 



3 4-029 



4 5-372 



5 6.715 



6 8.058 



7 9-401 



8 10.744 



9 12.087 



364. Utility of the Method. Where it is desirable that the 

 nitric oxid method be used, and at the same time heating be 

 avoided, the decomposition of a nitrate by means of metallic 

 mercury and sulfuric acid affords a convenient and accurate pro- 

 cedure. But, as a rule, there is no objection to the application 

 of the lamp except in the case of explosives, and in such cases the 

 mercury method appears to have no advantage over the ferrous 

 chlorid process. Nevertheless, in the hands of a skilled worker, 

 the results are reliable, and the process is a quicker one, on the 

 whole, than by distillation with ferrous chlorid and hydrochloric 

 acid. 



365. Volumetric Method of Gantter. The process proposed 

 by Gantter for determining the nitrogen volumetrically in Chile 

 saltpeter and other nitrates is based on the following principles : 51 



(1) If a nitrate be heated in contact with sulfuric and phos- 

 phorous acids, nitrous and phosphoric acids will be formed. 



(2) If nitrous acid be boiled with ammonium chlorid, nitrogen 

 will be quantitatively evolved from both compounds. These pro- 

 cesses are illustrated by the following formulas: 



(a) N 2 5 +P 2 3 =N 2 3 +P 2 6 . 



(b) N 2 O 3 +2NH 4 Cl- 2 N 2 +3H 2 O-f2HCl. 



51 Zeitschrift fur analytische Chemie, 1895, 34 : 26. 



