"normal." If it be desired to determine the absolute amount of nitrogen
separated from a nitro-cellulose, the following conditions must be
observed:--(1.) Accurate weighing of the nitro-cellulose; (2.)
Determination of the amount of air in the CO_{2}, and deduction of this
from the volume of gas obtained; (3.) Reduction of the volume of the gas
to the volume at 0° C. and 760 mm. pressure.[A]

[Footnote A: See also _Jour. Soc. Chem. Ind._, Dec. 1902, pages 1545-1555,
on the "Stability of Nitro-cellulose" and "Examination of Nitro-
cellulose," Dr Will.]

~Bergrnann and Junk~[A] describe a test for nitro-cellulose that has been
in use in the Prussian testing station for some years. The apparatus
consists of a closed copper bath provided with a condenser and 10
countersunk tubes of 20 cm. length. By boiling amyl-alcohol in the bath,
the tubes can be kept at a constant temperature of 132° C. The explosive
to be tested is placed in a glass tube 35 cm. long and 2 cm. wide, having
a ground neck into which an absorption bulb is fitted. The whole apparatus
is surrounded by a shield, in case of explosion. In carrying out the test,
2 grms. of the explosive are placed in the glass tube and well pressed
down. The absorption bulb is half filled with water, and fitted into the
ground neck of the glass tube, which is then placed in one of the tubes in
the bath previously brought to the boiling point (132° C.). The evolved
oxides of nitrogen are absorbed in the water in the bulb, and at the end
of two hours the tubes are removed from the bath, and on cooling, the
water from the bulb flows back and wets the explosive. The contents of the
tube are filtered and washed, the filtrate is oxidised with permanganate,
and the nitrogen determined as nitric oxide by the Schultze-Tieman method.
The authors conclude that a stable gun-cotton does not evolve more than
2.5 c.c. of nitric oxide per grm. on being heated to 132° C. for two