4.1 Apparatus

There are several methods for the determination of the nitrogen contents, but it is usually done using lunge nitrometer. For details of the apparatus refer to IS 1091- 1976, 'Specification for nitrocellulose'.

4.2 Procedure

About 0.56-0.62 gm of the dried sample (following the procedure given in 1.2) is taken in a tared weighing bottle. The sample is further dried for 4 hrs. in a water oven maintained at 75-80 °C. The weighing bottle with the sample is then cooled in a dessicator over calcium chloride and weighed accurately. The difference gives the mass of the material. 5ml of Analar sulphuric acid (94.5%) is added into the weighing bottle & the mass is made into slurry with a glass rod. The slurry is transferred into the cup of the Nitrometer & drawn into the Nitrometer by operating the stopcock taking care to avoid sucking air into the reaction tube. The weighing bottle & the cup of the Nitrometer are rinsed several times with 94.5% sulphuric acid using a total of 15ml for dissolving and rinsing. The reaction mixture is allowed to stand in Nitrometer arm for 15 minutes & then shaken vigorously for 2 to 3 minutes. The gas generated is allowed to cool to room temperature & the volume is measured under atmospheric pressure by adjusting the leveling tube.

% Nitrogen = [V x P x 0.02246] [(t+273)] x W

where
V = volume of gas in ml.
P = corrected barometric pressure in mm of mercury.
t = room temperature in °C.
W = weight of the dried material taken.