VOLUMETRIC METHOD OF GANTTER 423 



tion bulb is connected with A and B by the tubes a and b, as 

 shown. The tube d connects the apparatus with the gasvolu- 

 meter. 52 The bulb B serves as a pipette for the introduction 

 of the decomposing acid. The operation is conducted as follows : 

 Three cubic centimeters of the nitrate solution, containing no 

 more than 300 milligrams of the substance, are placed in the 

 flask A, with half a gram each of crystallized ammonium chlorid 

 and phosphorous acid. In the bulb B are placed seven cubic cen- 

 timeters of sulfuric acid, to which has been added one-third its 

 volume of water. Two cubic centimeters of acid are allowed to 

 flow from B into A. The apparatus is brought to a constant 

 temperature by being immersed in a large cylinder E, containing 

 water at a temperature which can easily be controlled. When 

 this constant temperature has been reached the apparatus is taken 

 from the cooling cylinder, which contains also a smaller cylinder 

 D, nearly filled with water and connected through f with the 

 measuring apparatus M. The barometer-tube F is half filled 

 with colored water, so that the pressure may be equalized before 

 and after the operation. The flask A is warmed very gently at 

 first, and the nitrogen evolved is conducted into D, driving an 

 equivalent volume of water into M. The evolution of the gas 

 must be carefully controlled and the heat at once removed if it 

 becomes too rapid. The appearance of a red color shows the 

 evolution of oxids of nitrogen, rendering the analysis inexact. 

 When the evolution of nitrogen has nearly ceased, the lamp is 

 removed and some more sulfuric acid allowed to flow into A 

 from B, after which A is again heated, this time to the boiling- 

 point. All vapors of hydrochloric acid produced are absorbed 

 by the soda-lye in C. The boiling is continued a few minutes, 

 but not long enough to darken the liquid in A. After replacing the 

 apparatus in the cylinder E, and bringing both temperature and 

 pressure to the same point as before the beginning of the opera- 

 tion, the volume of nitrogen evolved is determined by measuring 

 the water ki M. 



The apparatus is first set by using pure potassium or sodium 

 nitrate. Since the temperature and pressure do not vary much 

 M Zeitschrift fur analytische Chemie, 1893, 32 : 553- 



