Daily globe. [volume] (St. Paul, Minn.) 1878-1884, 1883-06-21
GUN-COTTON.
The POscer of the Terrible and Dangerou.
Explosive.
[Dr. Doremus. in the New York Sun


corning explosives, which l shall be
happy to demonstrate to him, if he will
honor me with his presence, at the Col
lege of the City of New York, or at
Bellevue Medical College. If gunpow-
| der is placed in a basket made of coiled
platinum wire, and is then inserted in a
glass jar arranged so that it can be ex-
! hausted of air by an air-pump, on apply
| ing current of electricity to the coil,
so as to render the wire red hot, the
gunpowder will neither explode nor burn
with flash. It will apparently boil,
with a purple light, and will require
from five to twenty seconds for its COM
plete combustion, depending on the
quantity of powder and the amount of
air removed.
All know that gunpowder has its own
supply of oxygen it does not require
any from the air; for we shut out the air
when we load apistol, rifle or a cannon.
The nitrate of potash furnishes the oxy-
gen for the carbon and sulphur of the
powder. Tie cause of the tardy COM
bustion of the gunpowder in the ex-
hausted receiver is the diminished
pressure.
But wrap the powder in paper, and we
have the frecracker; inclose the powder
in an iron sphere, and we have the
bomb-shell. AS the powder burns I'M
der increased pressure produced by its
own gases. it explodes with increased
force. An ounce or even a pound of
powder, when burnt in the open air,
produces no explosive sound-merely a
puff.
The Eliminates of silver or mercury
which are used in percussion caps will
also burn slowly when placed in the
platinum coil referred to and heated red
hot after the air has been exhausted
from the glass jar. Yet in the open air,
when fired, they will explode with
sharp sound.
If lock of gun-cotton (of the most
explosive kind), say foot in length, be
suspended in glass jar with said plat
mum coil and, aftsrremoving the pressure
OF the air by pump, if the coil is made
red hot by an electric current, the gun
cotton will not explode, nor will flame
or spark of fire be seen the gun-cotton
will gradually disappear.
Even under the pressure of the air,
or, in other words, in the open air,
small quantities of gun-cotton of the
most explosive variety when lighted do
not explode they merely burn with a
bright flash of light. When we prepare
gun cotton before a class in chemistry
we frequently place a lock of it on a
students hand and fire it to show how
quickly it burns for he scarcely feels
it. This is one of the trivial tests of its
good quality. Another is to place the
gun-cotton on gunpowder, then apply a
light. If it fails to ignite the powder it
is the explosive variety; if it sets fire to
the powder it is inferior in character.
Photographers gun-cotton, which is SOL
uble in alcohol and ether, and is used
for making collodion, will burn slower.
If placed on gunpowder it will ignite it.
Inc!ose the explosive variety of gun
cotton III a stout receptacle. Now fire
it, and it will exhibit three times the
force Of gunpowder.
If Superintendent Walling will fill
teaspoon with nitro glycerine and apply
to it lighted match, he will find that
the nitro-glycerine will quietly and
slowly burn, with green-colored fame,
because it is only subjected to the press
ure of the air. But if he places this
amount of nitro-glycerine in a closed
vessel and fires it, would advise him to
remain at respectful distance from it.
have placed fluid ounce of nitro
glycerine in metal cup, connected with
one pole of galvanic battery, and, ON
applying the opposite pole of the bat
terry to said liquid, have shown before
medical class that the nitro glycerine
burns tardily and without noise. With
said battery had previously fused and
volatilized platinum, iridium and other
refractory metals to demonstrate the in
tensity of the heat. Yet, if single
drop of ro-Glycerine is placed on a
smooth surface andstruck sudden blow
the explosion is stunning to the ear The
same law applies to giant powder, dyna.
mite, rend-rock and other terrific ex
piosives. They must have pressure to
exhibit their power. They burn qui-
city and slowly without it.