Pyrotechnics: The History and Art of Firework MakingBrock, Alan St. H. (Alan St. Hill)
History
Pyrotechnics: The History and Art of Firework Making
Brock, Alan St. H. (Alan St. Hill)
Fireworks
Of the fireworks of the fountain class, probably the first to develop
from the crude rocket form were the gerb and flower pot. The gerb, or
Chinese tree, contains a composition of saltpetre, sulphur, charcoal
and iron borings, with the addition—if more force is required, as
for instance to turn a device—of mealed gunpowder. Early makers used
mealed powder alone and “iron sand,” or cast-iron reduced to powder
by hammering. This composition is known as Chinese fire, and, as its
name implies, was introduced into Europe from the East. An interesting
article appeared in the “Universal Magazine” of 1764, written by
a Jesuit missionary on the subject of Chinese fireworks. In it he
describes the making of iron sand as follows:
“Old broken or useless pots serve generally for making this sand;
they are broken into pieces of the breadth of the hand, after
which, being made red-hot in the fire of a forge, they are thrown
in that condition into a trough filled with fresh water, where they
are left to cool. Thus calcined, the rust falls off in scales, and
they are easily reduced into sand, being first broken into parcels
of a finger’s breadth. The anvil and hammer used for this purpose
must be also of cast-iron, because steel flats the grains of sand.
It is necessary that the angles of those grains should be sharp, as
it is the angles that form the flowers.”
The word “gerb” is derived from the French word meaning a sheaf of
corn, and was first applied to water fountains.
The flower pot is charged with a composition formerly known as
“spur-fire,” from the resemblance in form of its coruscations to the
rowel of a spur. The effect produced is one of the most effective
when successful, but has the disadvantage for display work that the
effect is only appreciated at close quarters. The ingredients used are
lampblack, sulphur, red arsenic, saltpetre, with sometimes the addition
of charcoal and mealed gunpowder.
Of the smaller works of this division the squib and golden rain are
too well known to need description. The squib and its variations have
a choked case; the golden rain and similar works are left with an open
bore.
Squibs are generally filled with a composition of sulphur, saltpetre
and charcoal, sometimes steel filings, with a bounce of fine-grain
powder.
A curious firework, now almost obsolete, for which it is difficult to
find a class, is the five-pointed star. This work consisted of a case
having a diaphragm of plaster of paris or clay above the filling, below
which five holes are bored equidistant and at right angles to the axis.
The case is fired in the unusual position of horizontal with the end
towards the spectator, the fire playing all round the case, forming a
star. The composition used was mealed powder, sulphur, saltpetre, and
sulphuret of antimony. Ruggieri mentions this firework under the name
“Etoile fixé,” and it is mentioned by Jones, writing in 1765, but not
by Frézier.
Public-domain text, read in full here on John Shaqi.
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