The Arizona sentinel., 1889-10-19

Brown gunpowder was introduced in
1882. 1t has been generally supposed
that the invention was German, but q
few months ago Colonel Brackenbury
stated in London that England was the
first country to make slow powders,
and that the German powder came in
long after the experiments at Walth-
am Abbey. The chief characteristic
of brown powder is its slow rate OF
burning. This is due to the fact that
it contains very little sulphur and a
peculiar kind of charcoal. Sulphur is
powerful kindling agent, and any
powder may be slowed or quickened
by varying the proportions of this in
gredient. The composition of brown
or cocoa" powder was kept a secret
for a long time. but it is now known
that the German powder is composed
of seventy-nine per cent of potassium
nitrate, three per cent. of sulphur and
eighteen per cent. of hghtly-bal1ed
brown charcoal made from slightly
carbonized straw. Previous to 1882
the powder formula the world over
was about seventy-five per cent. of
potassium, ten per cent. of sulphur and
fifteen per cent. of charcoal. The Du
Points in the Brandywine, who supply
the Government with powder, have sue
ceeded in making brown powder that
has given as good results as the for
eign article.
Brown powder is made in hexagonal
prisms one inch long, pierced longi-
tudinally with a central hole. In
making up cartridges the prisms are
built up regularly like honey comb,
with the holes over each other, so as
to form continuous tubes through the
cartridge. The object of this is to
permit the gases to permeate through
the entire mass. When the charge is
ignited the flame and gases rush
through to the other end of the cart
ridge, infaming each prism in its CEN
tral hole, thus causing them to burn
from in out, consequently producing a
progressively increasing surface of
ignition and evolving increasing vol
umes of gas Hence brown powder is
sometimes called progressive, but
the term applies really to all powder.
fine grain as well as prismatic, be-
cause in the true sense of the word
powder is not an explosive such as gun
cotton or nitro-glycerine.
The velocity of combustion is great
est in fine-grain black powder, which
seems. to explode when ignited, so rap
idly is it consumed, and slowest in
brown powder. A prism of black
powder of the old composition when
ignited in open air burns in less than a
second, while similar grain of cocoa
powder is nearly sixty times as long in |
burning, giving off dense volumes of |
white smoke.
AS the velocity of combustion of |
black powder is almost instantaneous,
the pressure arising from it resembles
the force of a sharp, quick blow, and |
would impose upon the gun in which |
tits fired severe strains if the proiectile |
did not move at once and relieve it.
For this reason black powder can not |
be used in high-power guns which en-
ploy long heavy shell having upon
its rear end a band of soft metal the
diameter of which is greater than that
of the bore of the gun, so the shell can
not pass through the bore until this
metal is forced out into the grooves of
the rif1ing- Now, if the gun were
loaded with black powder the press
ure would rise to its maximum
almost at the instant of ignition be-
fore the shell would have time to
move, and the result would probably
be the destruction of the gun. The
case is very different with brown pow
der. When the charge is ignited the
pressure is low at first gradually ris-
ing until it is sufficient to start the
shell, the copper band is forced into
the grooves, and the projectile starts
on its flight, slowly at first, but with
velocity of 1000 feet per second when
it leaves the muzzle. AS the space be-
tween the shell and the charge in
creases the pressure of the gases would
rapidly fall were it not for the fact
9hat the powder is giving off constant
ly increasing volumes of gas. In this
way the pressure is maintained on the
projectile all the way to the muzzle,
thus greatly increasing its muzzle
velocity. 1t is clear, then, that brown
powder gives a much higher mean
pressure in the gun than black pow
der, and that the maximum pressure is
not reached until after the proiectile
is started. In a 6-inch steel breech-
loading rife the maximum pressure is
fifteen tons, and the pressure at the
muzzle from three to four tons.
The development of powder has
Jagged behind that of guns Before the
"steel age' of guns the tendency was
toward an increase of caliber only and
consequently larger charges, but as
the charge of quick-burning powder
increased, so did the pressures, and