Evening journal., 1915-08-09
ORDNANCE EXPERT
explains EXPLOSIVES
Major E. P. O'Hern De-
ScribeS Manufacture
and Use of Powders
TELLS OF UNITED
STATES SUPPLIES

WASHINGTON, Aug. s-While sew
sral million pounds Of powder are be-
ng burned weekly on the battlehelds
Of Europe and discussion is rife on
he American manufacture of the ma
lerial, an article on explosives just is
sued by the Smithsonian Institution
gives much timely information on the
subject.
The paper is written by Major Ed
ward P O'Hern. of the ordnance de-
partment United States army, and
deals with the Importance of the so
called explosives and the increasing
extent Of ther use and production, as
we'll as their composition, uses.
method of employment and the re-
suits accomplished.
AN explosive" says Major O'Hern.
lis a substance of which the MOLE
cules are made up of number of
atoms or units rather loosely bound
together in an unstable condition,
ready to seek new and simpler COM
binations 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 a wire heated by
an electric current. When started.
the heat and shock developed will
cause a continuation of the action
throughout the mass of the explosive.
"The enormous power that can thus
be developed from a comparatively
small quantity of material is indicated
by the thousands of fragments into
which a 12-inch armor-piercing pro-
jectile was broken by the detUnation
of a bursting charge about IL per
cent of its weight"
Defines Three Glasses.
The author divides explosives into
three classes. progressive or propell-
ing explosives. known as low explo-
sives decorating explosives or high
explosives, and detonators or full
inmates. For all classes the effect Of
the explosion is dependent upon the
quantity of gas and heat developed
per unit of weight and volume of the
explosive, the rapidity of the reaction,
and the character of the confinement.
If any. given the explosive charge
The rapidity of reaction varies great
ly with different explosive substances
and with the manner in which the ex-
plosion is started
Black gunpowder, smokeless powder
and black blasting powders are known
as low explosives, for certain of which
such as smokeless powder. the explo-
sion does not differ in principle from
the burning of piece of wood or other
combustible. The combustion is very
rapid but is a surface action proceed
ing from layer to layer until the grain
Is consumed. Such materials are
Known as low or progressive explo-
sives, although the total power devel-
0ped through the combustion of a unit
weight may be very great and would
be destructive unless properly con-
trolled.
High Explosives Action.
in high explosives, such as dynamite
nitro-glycerin, guncotton, some blasting
powders. and most of the permissible
explosives" approved by the Unitec
States Bureau of Mines for use in mine:
where gas explosions are liable to occur
the progress Of the explosive reaction is
not by burning from layer to layer, bui
the breaking up of the initial molecules
gives rise to an explosive wave which
is transmitted with great velocity in al
directions throughout the mass anC
causes its almost instantaneous conver
sior into gas.
The velocity of propagation OF the
detonating wave has been determined
for some materials to be more than
10000 feet a second, or approximately
four miles a second. This form OF
material is used in shells and for
bursting purposes. The progressive
emission of a gas from a low explos-
i've such as burning gunpowder. pro-
duces pushing effect upon a pro-
jectile. whereas the sudden conver-
sion of an equal weight of material
into gas. as would happen with a high
explosive such as dynamite or nitro
slycerin, would develop such high
pressure and shattering effect as to
rupture the gun.
The action of Eliminates is much
more brusque and powerful than tina.
of the high explosives. Since they can
be detonated by shock or the applica-
ton of heat, they are used in primers
and fuses to start action in both low
and high explosives. One of the most
important Eliminates is illuminate OF
mercury, which produces a pressure
Of about $4,000 atmospheres.
At no time in the history of the worlt
have explosives played such a might,
part IN deciding the destiny of nation
as they are playing today in the prose
eution of the general European wal
Their extensive Use in the mighty en-
gines of destruction. such as the subma
rne, mine, the torpedo and in proiectile
thrown from cannon to great distance
with marvellous accuracy. is resulting Il
loss OF life and destruction of propert,
on an unprecedented scale.
VesorlbeS Powder DeveIOpmenf.
beglnning with black powder, the
earliest record of which in actual war
was in the fourteenth century tbe AM.
nor follows the development Of pow
der through its early stages of brown
powder to the two principal forms OF
smokeless powder for military pur.
poses nitro-cellulose and nitro-elvcer-
Inc, stating that the use is quite evenly
divided, 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
German navy using the latter.
He then gives much detailed infor-
nation concerning the manufacture
life. source of supply and tests OF
smokeless powder manufactured
from nitro-ceilulose or gun-cotton
Subjects relating to life of guns
bursting proiectiles, high-explosive
shells. shrapnel fuses, aeroplane
houbs means of ienitine eVnIo-i,-or