F.M. Horn (_Zeitschrift fuer angewandte Chemie_, 1892, p. 358) has devised
a form of nitrometer (Fig. 43) which he has found especially useful in the
examination of smokeless powders. The tap H is provided with a wide bore
through which a weighed quantity of the powder is dropped bodily into the
bulb K. From 4 to 5 c.c. of sulphuric acid which has been heated to 30 deg. C.
are then added through the funnel T, the tap H being immediately closed.
When the powder has dissolved--a process which may be hastened by warming
the bulb very carefully--the thick solution is drawn into the nitrometer
tube N, and the bulb rinsed several times with fresh acid, after which
operation the analysis is proceeded with in the usual way.

Dr Lunge's method of using a separate nitrometer in which to measure the
NO gas evolved to the one in which the reaction has taken place, the gas
being transferred from the one to the other by joining them by means of
indiarubber tubing, and then driving the gas over by raising the pressure
tube of the one containing the gas, the taps being open, I have found to
be a great improvement.

1 c.c. NO gas at 0 deg. and 760 mm.
Equals 0.6272 milligrammes (N) nitrogen.
" 1.343 " nitric oxide.
" 2.820 " (HNO_{3}) nitric acid.
" 3.805 " (NaNO_{3}) sodium nitrate.
" 4.523 " (KNO_{3}) potassium nitrate.

~Champion and Pellet's Method.~--This method is now very little used. It
is based upon the fact that when nitro-cellulose is boiled with ferrous
chloride and hydrochloric acid, all the nitrogen is disengaged as nitric
oxide (NO). It is performed as follows:--A vacuum is made in a flask,
fitted with a funnel tube, with a glass stopper on the tube; a delivery
tube that can also be closed, and which dips under a solution of caustic
soda contained in a trough, and the end placed under a graduated tube,
also full of caustic soda. From 0.12 to 0.16 grm. cotton dissolved in 5 to
6 c.c. of sulphuric acid is allowed to flow into the flask, which contains
the ferrous chloride and hydrochloric acid, and in which a vacuum has been
formed by boiling, and then closing the taps. The solution is then heated,
the taps on the delivery tube opened, and the end placed under the
collecting tube, and the NO evolved collected. The NO gas is not evolved
until the solution has become somewhat concentrated. Eder substituted a
solution of ferrous sulphate in HCl for ferrous