Evening star. [volume] (Washington, D.C.) 1854-1972, 1915-08-07
USE OF EXPLOSIVES
INCREASED BY WAR
Composition and Methods of
Production Described by
Mai: E. P. 0'Hern.
DIVIDES THE PRODUCT
INTO THREE CLASSES
Molecules Made Up of Atoms or
Units Possessing Great
Latent Force.

While several million pounds of pow
der are being burned weekly on the
battlefields of Europe and discussion
is rife on the American manufa cture
of the same. an article on explosives
just issued by the Smithsonian Institu-
ton gives much timely information on
the subject, The paper is written by
Maj Edward P. O'Hern of the ordnance
department, United States Army, and
deals with the Importance of the So
called explosives and the increasing
extent of their use and production, as
we'll is their composition, uses. method
of employment, and the results accom-
plished.
AN explosive" says Maj OHern, us
a substance of which the molecules are
made up of a number of atoms or units
rather loosely bound together in an
unstable condition, ready to seek new
and simpler combinations upon the
furnishing of a sufficient motive force
to start the operation. This is usually
supplied through a primer ignited by
a slow-burning fuse, or by wire heat
ed by an electric current. When start
ed, the heat and shock developed will
cause continuation of the action
Throughout the mass of the explosive
The enormous power that can thus pe
developed from a comparatively small
quantity of material is indicated by the
thousands of fragments into which
twelve-inch armor-piercing pro1ectlle
was broken by the detonation of a
bursting charge about 5h per cent OF
its weight
Divided Into Three Glasses.
The author divides explosives into
three classes. progressive or propelling
explosives. known as low explosives;
decorating explosives. or high explo-
sives, and decorators or Eliminates.
For all classes the effect of the explo-
sion is dependent upon the quantity
of gas and heat developed per UNI vi
weight and volume of the explosive,
the rapidity of the reaction and the
character of the confinement. II any,
given the explosive charge. The raPia-
ity of reaction varies greatly with az
ferent explosive substances and with
the manner in which the explosion is
started. ,ao,
and black blasting powders are known
as low explosives, for certain OF wnlch'
such as smokeless powder. the ex-
plosion does not differ in principle
from the burning of a piece OF WOOD
or other combustible. The combustion
is very rapid, but is a surface action,
proceeding
the grain is consumed. Such materials
are known as low or progressive eX-
plosives, although the total power de-
veloped through the combustion or
unit weight may be very great ana
would be destructive unless properly
controlled.
Progress of Explosive Reaction"
In high explosives such as dynamite,
nitroglycerin, guncotton, some blasting
powders, and most of the permissible
explosives" approved by the United
States bureau of mines for use in
mines where gas explosions are liable
to occur, the progress of the explosive
reaction is not by burning from layer
to layer, but the breaking up OF the
initial molecules gives rise to an ex-
plosive wave, which is transmitted with
great velocity in all directions through
out the mass and causes its almost in
Simultaneous conversion into gas. The
velocity of propagation of the deto-
mating kave has been determined FOR
some materials to be more than 10000
feet per second, or approximately four
miles per second; this form of material
is used in shells and for bursting pur-
poses.
The progressive emission of gas
from a low explosive such as burning
gunpowder produces a pushing effect
upon a projectile, whereas the sudden
conversion of an equal weight of mate
rial into gas, as would happen with
high explosive, such as dynamite or
nitroglycerin, would develop such high
pressure and shattering effect as to
rupture the gun.
The action of Eliminates is much more
brusque and powerful than that of the
high explosives Since they can be de-
tonated by shock or the application of
heat, they are used in primers and
fuses to start action in both low and
high explosives. One of the most i'm
portant Eliminates is illuminate of mer
curry, which produces pressure CT
about $4,000 atmosphereS.
Part Played by Explosives.
At no time in the history Of the world
have explosives played such = mighty
part in deciding the destiny of nations
as they are playing today in the prose-
cution of the general European war
Their extensive use in the mighty en-
gines of destruction such as the sub
marine mine, the torpedo, and in pro-
jectiles thrown from cannon to great
distances with marvellous accuracy, is
resulting in loss of life and destruction
of property on an unprecedented scale
Beginning with black powder, the
earliest record of which in actual war
was in the fourteenth century. the
author follows the development of pow
der through its early stages OF brown
powder to the two principal forms of
smokeless powder for military pu--
poses, nitrocellulose and nitroglycerin,
stating that the use is quite evenly di-
vided. the United States Army and
Navy, the French army and navy. and
the German army using the former, and
the British army and navy and the Ger
man navy using the latter.
He then gives much detailed informa-
ton concerning the manufacture, life,
source of supply and tests of smokeless
powder manufactured from nitrocellu-
lose or guncotton. Follwing which, sub
jects relating to life of guns, bursting
charges for projectiles, armor- piercing
projectiles, high explosive shells. shrap-
mel. fuses. aeroplane bombs. means of
igniting explosives, mines, torpedoes,
and the storage and shipment of ex-
plosives in the United States are Cis-
cuSsed.