be true if
the temperature were raised to 50 deg. to 55 deg. C. The process is as follows:--
The paper is nitrated in the cage (Fig. 25), the bottom of which is formed
by the flanged plate C, fastened to the bottom of the internal cylinder B.
After nitration the cage is carried to a wringer, which forms the basket,
and the acids removed. Finally, the cage is taken to a plunge tank, where
the paper is removed from the cage by simply pulling out the central
perforated cylinder B. Fig. 26 shows the nitrating pot, with its automatic
cover. The plunge tank is shown in plan and section in Figs. 28 and 29.
This apparatus is suitable for the nitration of cotton fibre in bulk at
high or low temperatures. Other methods that have been patented are
Mowbray's (U.S.P., No. 434, 287), in which it is proposed to nitrate paper
in continuous lengths, and Hyatt's (U.S.P., No. 210, 611).

[Illustration: FIG. 24.--CENTRAL PERFORATED CYLINDER.]

[Illustration: FIG. 25.--THE CAGE. WHITE AND SCHUPPHAUS' NITRATING
APPARATUS.]

[Illustration: FIG. 26.--CELLULOID NITRATING POT.]

[Illustration: FIG. 27.--ANOTHER VIEW.]

[Illustration: FIGS. 28, 29.--PLUNGE TANK, IN PLAN AND SECTION.]

~The Acid Mixture.~--Various formulae have been published for producing
soluble nitro-cellulose. In many instances, although the observations were
correct for the single experiment, a dozen experiments would have produced
a dozen different products. The composition of the acids used depends upon
the substance to be nitrated, and the temperature at which the nitration
will be worked. Practically there are three formulae in general use--the
one used by the celluloid manufacturers; another in which the cotton is
nitrated at high temperatures; and a third in which the temperature of the
immersion is low, and the time of nitration about six hours. Of the three,
the best method is the last one, or the one in which the cotton is
immersed at a low temperature, and then the reaction allowed to proceed in
pots holding from 5 to 10 lbs. of cotton. The formula used by the
celluloid manufacturers for the production of the low form of nitrated
product which they use is:--

Sulphuric acid 66 parts by weight.
Nitric acid 17 " "
Water 17 " "

Temperature of immersion, 30 deg. C. Time, twenty to thirty minutes.

The cellulose is used in the form of tissue paper 2/1000 inch thick, 1 lb.
to 100 of acid mixture. The nitro-cellulose produced