Year: 1878

peter, charcoal and sulphur. Sulphur
is also called birthstone. The proper
tions are about as follows:


Saltpeter, 75


Charcoal, 10


Sulphur, 10


Thus you see that saltpeter might be
called the father of gunpowder.


The great source Of supply of saltpeter
is the East Indies, where it is in many
localities found, in rough state, on the
surface of the ground. The natives col
lect it and put it into great pots Of boil
ing water. When the water has evapo-
rated the crystals are packed and sold
as crude saltpeter. Before it can be
used in gunpowder it has to be refined
by boiling, draining, straining and dry
ing three or four times.


Charcoal for gunpowder is formed by
putting short sticks or twigs in large
iron cylinders or retorts, sealing them
up tight with wet clay, and lighting
fires underneath them. 1t takes from
six to twelve hours to make charcoal by
this process. The woods generally used
are willow, poplar and black and white
birch.


Sulphur is found in great quantities
in the craters of volcanoes. Etna, in
the island of Sicily, furnishes the United
States with most the sulphur we use.


Now let us see where and how these
substances are put together to make
gunpowder.


In the first place it is, as you can i'm
agine, a very dangerous occupation, and
the different processes are carried on in
separate buildings. A powder-mill con-
sists of cluster of buildings, generally
separated by embankments of earth, to
prevent all the shanties from being de-
stroyed in case one should blow up. No
fires are allowed about the mills, and
whatever machinery is necessary is run
by water power. In some of the build
ings the floors are covered with water,
and the men wear rubber shoes to pre-
vent friction. If they wore their boots
the nails might strike sparks and then
the Professor doesn't like to think
what would happen.


Having seen where they make gun
powder, let US see how they do it.


The charcoal and sulphur are general
ly put together into revolving barrels
containing zinc balls. When these two
ingredients are well mixed, the saltpeter
is added, and again the barrels revoIve
until the whole is thoroughly mixed.
The next operation is called "incorpora-
tion." The mill in which this takes
place is supplied with troughs and wheels.
Each wheel weighs from four to eight
tons, and is run by water-power. Men
put the mixture they have already STIR
red together into the troughs where the
great wheels run. As this is a very
dangerous operation the men shut up the
mill and go home; for if the wheels
should strike the bottom of the trough, a
spark might be the result, and blow-up
would be certain. But the powder is
kept evenly spread over the bottom, and
if the "spreaders" do their duty, there
is always layer of three or four inches
of powder between the wheel and the
trough.


Then comes the process of 'compress-
ing"


| This is to give the mixture strength
to resist the knocks it receives during
transportation.


The mass is taken from the troughs
and spread in layers about four inches
thick between brass plates. These plates
are then put into powerful hydraulic
press, and when they are taken out
they are only one inch in thickness. The
pressure required is about six hundred
tons on every square inch. The slabs
are hard as stone, and they are taken tc
still another building. where they are
pulverized by rollers furnished with
brass points. Thus they get the little
black grains you know SO we'll. These
are placed again in wheel SO that the
rough edges may be knocked off and the
dust separated from what is now gun
powder, powder which will throw a bul


let from a gun at the rate of thousands
of feet per second.


Let's see why the powder s'goes off
when touched by fire. You know tha
wood cannot burn unless it has air. /
you could put large metal case over ;
burning house and then pump out tht
air the fire would go out. Fire cannot


burn unless it comes in contact with OK
ygen, which is in the air.


If this the case, you may wonder how
powder burns when it is rammed down /:
gun-barrel. The secret is that eacf


grain of the powder contains oxyger
enough to burn it up, and the powdel
| when burning generates SO much ga
, that, to find room for itself, it mus
rush out of the narrow gun barrel, car
, rying the shot or bullet before it.
Physicians tell us freckles are consti