The Chemistry of Powder and Explosives - Sciencemadness Dot Org

90 PYROTECHNICS
must be protected from rusting by previous treatment with
paraffin or linseed oil.
Prismatic fountains, floral bouquets, etc., are essentially colored
gerbs. Flower pots are supplied with wooden handles and
generally contain a modified black powder composition with
lampblack and sometimes with a small amount of granulated
black powder. In the charging of fountains and gerbs, a small
charge of gunpowder is often introduced first, next to the clay
plug which closes the bottom of the tube and before the first
scoopful of composition which is rammed or pressed. This makes
them finish with a report or bounce.
Fountains
Fountains are designed to stand upon the ground, either upon
a flat base or upon a pointed wooden stick. They are choked
slightly more than gerbs, and have heavier, stronger cases to
withstand the greater pressures which eject the fire to greater
distances.
The "Giant Steel Fountain" of Allen F. Clark is charged with
a mixture of saltpeter 5 parts (200 mesh), cast-iron turnings 1
part (8 to 40 mesh), and red gum 1 part (180 to 200 mesh). For
loading, the mixture is dampened with 50 per cent alcohol. The
case is a strong paper tube, 20 inches long, 4 inches in external
diameter, with walls 1 inch thick, made from Bird's hardware
paper. It is rolled on a machine lathe, the paper being passed
first through a heavy solution of dextrin and the excess of the
gum scraped off. The bottom of the case is closed with a 3-inch
plug of clay. The composition will stand tremendous pressures
without exploding, and it is loaded very solidly in order that it
may stay in place when the piece is burned. The charge is
rammed in with a wooden rammer actuated by short blows, as
heavy as the case will stand, from a 15-pound sledge. The top
is closed with a 3-inch clay plug. A ys-i ncn hole is then bored
with an auger in the center of the top, and the hole is continued
into the charge to a total depth of 10 inches. The composition is
difficult to light, but the ignition is accomplished by a bundle
of six strands of black match inserted to the full depth of the
cavity and tied into place. This artifice produces a column of
scintillating fire, 100 feet or more in height, of the general shape
of a red cedar tree. It develops considerable sound, and ends sud-