r than 14 per cent., it
probably contains considerable quantities of the lower nitrates, and
perhaps some non-nitrated cellulose as well (C_{6}H_{10}O_{5})_{x}, which
of course would also lower the percentage of nitrogen.

The most expeditious method of determining the nitrogen in these nitro
bodies is by the use of Lunge's nitrometer (Fig. 41), and the best way of
working the process is as follows:--Weigh out with the greatest care 0.6
grm. of the previously dried substance in a small weighing bottle of about
15 c.c. capacity, and carefully add 10 c.c. of concentrated sulphuric acid
from a pipette, and allow to stand until all the cotton is dissolved. The
nitrometer should be of a capacity 150 to 200 c.c., and should contain a
bulb of 100 c.c. capacity at the top, and should be fitted with a Greiner
and Friederich's three-way tap. When the nitro-cotton has entirely
dissolved to a clear solution, raise the pressure tube of the nitrometer
so as to bring the mercury in the measuring tube close up to the tap. Open
the tap in order to allow of the escape of any air bubbles, and clean the
surface of the mercury and the inside of the cup with a small piece of
filter paper. Now close the tap, and pour the solution of the nitro-cotton
into the cup. Rinse out the bottle with 15 c.c. of sulphuric acid,
contained in a pipette, pouring a little of the acid over the stopper of
the weighing bottle in case some of the solution may be on it. Now lower
the pressure tube a little, just enough to cause the solution to flow into
the bulb of the measuring tube, when the tap is slightly opened. When the
solution has run in almost to the end, turn off the tap, wash down the
sides of the bottle, and add to the cup of the nitrometer; allow it to
flow in as before, and then wash down the sides of the cup with 10 c.c. of
sulphuric acid, adding little by little, and allowing each portion added
to flow into the bulb of the nitrometer before adding the next portion.
Great care is necessary to prevent air bubbles obtaining admission, and if
the pressure tube is lowered too far, the acid will run with a rush and
carry air along with it.

[Illustration: FIG. 41.--ORDINARY FORM OF LUNGE NITROMETER.]

The solution being all in the measuring tube, the pressure tube is again
slightly raised, and the tube containing the nitro-cotton solution shaken
for ten minutes with considerable violence. It is then replaced in the
clamp, and the pressure relieved by lo