The Chemistry of Powder and Explosives - Sciencemadness Dot Org

NITROSTARCH 273
At the beginning of an analysis, the reaction bulb and the measuring
bulb and the capillary tubes at the tops of the bulbs are completely
filled with mercury. A sample of about 1 gram of nitrocellulose is
weighed in a small weighing bottle, dried for an hour and a half at
100°, cooled in a desiccator, and weighed accurately. A little 95% sulfuric
acid is poured onto the nitrocellulose and the whole is washed
into the reaction bulb. The weighing bottle is rinsed out with several
small portions of sulfuric acid, the same acid is used for rinsing the
cup and is finally introduced into the reaction bulb, until altogether
about 20 cc. of acid has been used, care being taken that no air is
introduced. The mercury reservoir is lowered to give a reduced pressure
in the reaction bulb and the bulb is shaken gently, the stopcock
at its bottom being open, until the generation of gas has practically
ceased. The bulb is then raised until the level of the mercury drops
nearly to its lower shoulder, the stopcock is closed, and the bulb is
shaken vigorously for 3 minutes. The cock is opened and the apparatus
is allowed to stand for several minutes. The mercury level is then adjusted
as before, the cock is closed, and the shaking is repeated for
another 3 minutes. Finally the gas is transferred to the measuring bulb
and allowed to stand for about 20 minutes. The measuring bulb and
the compensating bulb are then adjusted in such fashion that the
mercury in both stands at the same level and that the mercury in
the compensating bulb stands at the point indicated by the paper strip.
The volume in the measuring bulb is then read. After each determination
the reaction bulb is rinsed out twice with concentrated sulfuric
acid.
In practice it is convenient to standardize the nitrometer from time
to time by means of a sample of pure potassium nitrate (13.85% N)
or of nitrocellulose of known nitrogen content.
The nitrometer is dangerous to one who does not understand it fully.
The closing at the wrong time of the stopcock at the bottom of the
reaction bulb may result in the explosion of that vessel and the throwing
about of glass and of acid.
Nitrostarch
Nitrostarch 105 is manufactured and used in the United States,
but has not found favor in other countries. In all the early attempts
to manufacture nitrostarch, the starch was dissolved in
strong nitric acid and the nitric ester was precipitated by mixing
the solution with sulfuric acid or with the spent acid from some
105 The article by Urbanski and Hackel in Z. ges. Schiess- u. Sprengstoffw.,
30, 98 (1935), is accompanied by an extensive bibliography.