no ARTIFICIAL NITROGENOUS MANURES 



sodium chloride, and sodium sulphate found. If the 

 result is to be returned in terms of nitrogen, i part of 

 NaNOg contains 0-164 part of N. 



If it is desirable actually to estimate the nitrogen 

 present, this should be done by one of the methods 

 described below. 



Estimation of Nitrogen in Sodium or Potassium Nitrate, 



93. ici) Nitrometer Method. — When strong sulphuric 

 acid is added to the solution of a nitrate in presence of 

 mercury, the nitrogen is liberated as nitric oxide. 



2KNO3+ 3Hg2SO,+4H2S04 



= K2SO,+6HgS04+2NO + 4H20. 



The percentage of nitrogen is calculated from the 

 amount of liberated NO. One litre of NO at N.T.P.i 

 weighs 1-344 grams. 



Apparatus. — The Lunge nitrometer (Fig. 18) con- 

 sists of two vertical glass tubes, A and B, connected at 

 the foot by a length of stout-walled rubber tubing, and 

 attached by clamps to a suitable stand. The tube B is 

 plain, and is used as a levelling tube, but A is graduated 

 from the top downwards, usually a total volume of 

 50 c.c, reading to yV c.c. The top of this tube is 

 contracted and ends in a three-way tap, by means of 

 which it can be connected either with the reservoir d 

 or the capillary tube e. It may also be shut off from 

 both. 



Procedure. — The tube B is raised and mercury 

 poured in until it just reaches the glass tap in A and 

 fills the bottom 2 inches of B. This condition is obtained 

 by raising or lowering B as required. The tap is now 

 closed and the levelling tube clamped in position. 



About o- 1 to 0-2 gram of the sample of nitrate of 



^ Normal temperature and pressure, 0° C. and 760 mm. 



