I *

TOO

NITROGEN COMPOUNDS

means of the hot-water jacket surrounding the mixing trough. Incorporation
requires at least half an hour.

The paste thus obtained is transferred from the mixing house to the cartridge
huts, in which it is made into cartridges by an Archimedean screw machine of the
type shown in Fig. 37 ; the cylinder of paste issuing from a nozzle of required
diameter is cut into the lengths appropriate for each size of cartridge.

Homogeneity, stability,
complete absorption of nitro-
glycerine, and freedom from
tendency to exude are of the
highest importance in these
explosives.

Blasting gelatine is an
arnber-coloured, translucent,
elastic mass which stiffens-
somewhat as time elapses.

FIG. 37. -Cartridge Mixing Machine for If ™jll madcl ^resists the

Gelatine Explosives. conditions of the test for

exudation and stands the
heat test for a longer period

than the minimum of ten minutes. It explodes at 204° C. if heated slowly (Hess),,
and at 240° C. if the heating is rapid. It is also exploded by a blow of 3^ kg.-m!
between steel and steel, but is much more sensitive to shock when fro/en.

Gelatine dynamite is equally sensitive in its normal soft condition and when
frozen, and in both cases is exploded by a weaker blow than is blasting gelatine.
The insensitiveness of the latter when it contains camphor is somewhat remarkable.
The shattering effect of gelatine dynamite is less than that of blasting gelatine,
which is only used for very tough rock or for military purposes, and resembles
nitro-glycerine itself in its effects.

Among racent suggestions for the production of gelatinous explosives maybe mentioned those
of Schachtebeck (British Patent, 22.645, 1902) and Bichel (British Patent," 23,846, 1902). In
the former, ammonium nitrate is added to a gelatine consisting of glue or dextrin, glycerine and
water, and this is incorporated with a nitro-glycerine gelatine and a "carbohydrate. In the latter,
glue is dissolved in glycerine, and nitro-glycerine is added. Collodion cotton or a suitable dope
such as wood-flour and potassium nitrate may be added before the nitro-glycerine.

Picric Acid and Trinitrotoluene

( /°H ^

Picric acid or trinitro-phenol, \C0H2^(NOo)J, the oldest organic dye-stuff, has.

been used extensively for filling shells, and Its salts have formed constituents of
priming compositions and of powders used as propellants. The honey-yellow colour
of the molten acid suggested the name Melinite, which it receives in France, while
in other countries it is designated Lyddite, Pertite, Ecrasite, or Schimose. Its.
melting point, 122.5° C., is inconveniently high, so in order to secure greater ease
in manipulation and less risk a quantity of a soluble- substance sufficient to depress,
its melting point considerably is added to it. Dinitro-toluene, mononitro-naphthalene,
and camphor have been used for this purpose. Girard (British Patent, 6,045, I9°5)
gives a list of melting points of explosive mixtures of this kind :—

Mixture in Equimolecular Pro-
portions of—

Trmitro-phenol -

Nitro-naphthalene -

Trinitro-phenol -

Dinitro-toluene -

Trinitro-phenol -

Trinitro-cresol -

M,P. M.P. of Mixtuie.
122° C.\ or
61'C./ 49 C'
122° C.\ -> n
71° C.) 47 C-
122° C.) » s*
107° C.) 7° C.