MODERN FIREWORK COMPOSITIONS
Ruggieri may be regarded as the last of the ancients. It is true that
his book shows a marked advance on anything that had gone before,
also that he appears to have been one of the first, if not actually
the first, to introduce the use of metal salts in the production of
colour. But he makes no reference to the use of chlorate of potash, and
it is the introduction of this salt into pyrotechny which marks the
commencement of the modern epoch of the art.
This earliest use of chlorate, or as it was then called, oxymuriate
or hyperoxymuriate of potash, appears to have been soon after its
discovery in 1786 by Berthollet. Samuel Parkes, in a work on chemistry
written in 1811, says: “The shocking death of two individuals in
October, 1788, and the burns others have suffered by it, render it
feared by chemists in general,” that is in conjunction with sulphur and
charcoal.
He later remarks that notwithstanding this accident “the French have
since —— actually employed in one of their campaigns gunpowder made
with oxymuriate of potash instead of saltpetre,” and adds that a Scotch
clergyman had taken out a patent for the use of a powder containing
chlorate of potash to be fired by percussion.
This patent, granted in 1807, is the first for the percussion system in
firearms.
The use, however, of chlorate of potash in propellant compositions
presents no very great advance in pyrotechny, however revolutionary
may have been the introduction of the percussion system into the
manufacture of firearms.
It is its use in the production of colour that marks the modern epoch.
The exact date of this innovation appears to be about 1830.
A Belgian lieutenant of artillery, Hippert by name, published in 1836
a translation of a work by Captain Moritz Meyer, of the Prussian
Artillery, on the application of chemistry to artifices of war.
In a chapter devoted to coloured fires he gives several formulæ
containing chlorate of potash. Although this appears to be the first
published notice of its use, it seems likely that by the time the book
was published that it was fairly well established.
Meyer concludes his remarks on coloured composition by saying that the
English at that time made use of coloured rockets for signalling at
sea, and had succeeded in producing ten different shades, “which are
quite sufficient for the purpose of signalling particular pieces of
information.”
This seems rather to indicate that the elaboration if not the first
introduction of chlorate of potash into pyrotechny may be attributed to
this country.
His mention of ten distinguishable tints, however, is somewhat
optimistic. During the late war it was found that to avoid any chance
of a mistake in code signals only three colours could be used for
long-distance signalling, namely, red, green, and white.
It is curious that Meyer makes a mistake over the first composition
he mentions. He describes a light composition of chlorate of potash
and sugar, which he says burns with a red light. In fact, however, the
light so produced is a bluish white, similar to the so-called blue
shipping light.
The directions he gives for the preparation of other colours are as
follows:
“A powder which burns with a green flame is obtained by the addition of
nitrate of baryta to chlorate of potash, nitrate of copper, acetate of
copper.
“A white flame is made by the addition of sulphide of antimony,
sulphide of arsenic, camphor.
“Red by the mixture of lampblack, coal, bone ash, mineral oxide of
iron, nitrate of strontia, pumice stone, mica, oxide of cobalt.
“Blue with ivory, bismuth, alum, zinc, copper sulphate purified of its
sea water (_sic_).
“Yellow by amber, carbonate of soda, sulphate of soda, cinnabar.
“It is necessary in order to make the colours come out well to animate
the combustion by adding chlorate of potash.”
These formulæ, if somewhat incoherent, and clearly showing a want of
experimental verification, indicate a real advance in pyrotechnic
chemistry, not only by the addition of chlorate of potash, but by the
multiplication of the number of metal salts used.
At the same time it is evident that the old alchemistic ideas were not
entirely extinct by the use of such ingredients as ivory, mica, and
pumice stone.
However, there can be no doubt that from the third decade of the
nineteenth century dates the modern era of the pyrotechnic art. From
this date onward chemical ingredients, metals and their salts as they
were provided by the commercial chemist were eagerly taken and tested
by the pyrotechnist, and adopted or rejected on their merits. And from
this date begins the rapid elimination of useless additions.
Of those compositions given above the following salts are at present
in use: nitrate of baryta, sulphide of antimony, sulphide of arsenic,
nitrate of strontia, copper sulphate, carbonate of soda, and chlorate
of potash.
Zinc, alum, lampblack, and oxide of iron are also used, but not for the
purpose indicated.
Nitrate of copper and sulphate of soda would both be valuable
ingredients, but their unstable nature prevents their use under modern
conditions.
Meyer also describes the use of salts to tint an alcohol flame, which
is merely an elaboration of Ruggieri’s palm tree and of little interest
at the present time.
The next name prominent in pyrotechny is that of F. M. Chertier, who
published in 1854 his “Nouvelles recherches sur les feux d’artifice,”
after having published a pamphlet on the subject about twenty-five
years previously.
In this work Chertier devotes most of his attention to the subject of
colour, and although new ingredients have been introduced which were
either unknown or were not then available on account of expense or
other causes, since the time of his writing, yet there can be no doubt
that Chertier stands alone in the literature of pyrotechny and as a
pioneer of the modern development of the art.
Tessier, in the introduction to his “Treatise on Coloured Fires,”
published in 1859, whilst paying tribute to Chertier’s work, regrets
that he only possessed “quite superficial notions of chemistry.” Here
speaks the chemist. The writer recently asked a pyrotechnic chemist of
many years’ experience, whose knowledge of pyrotechnic chemistry is
probably second to none, his opinion of Tessier’s book, and received
this answer. “Tessier’s book contains too much chemical theory and too
little pyrotechnic practice.” There speaks the pyrotechnist.
The writer, as he has before remarked, has no wish to belittle the
value of the chemist’s work in relation to pyrotechny, but a knowledge
of chemistry is not the most important attribute of the successful
pyrotechnist.
As in other arts so in pyrotechny, experience and natural aptitude are
the first essentials.
Chertier may have had little knowledge of chemistry, but in spite
of or perhaps because of his lack of chemical knowledge, he was able
to produce a work which, from the point of view of the practical
pyrotechnist, has never been equalled.
His researches were conducted by practical experiments; he had one
end in view, namely, pyrotechnic effect, and by exhaustive trials of
the materials obtainable, unbiased by theoretical consideration, he
succeeded in advancing the art to a stage undreamed of a few years
previously. It is true that many of his formulæ are not in use to-day,
in this country that is, on account of the danger of using sulphur or
sulphur compounds in conjunction with chlorate of potash; but there can
be no doubt that his writings and research work laid the foundation of
modern pyrotechnic practice.
Once the theory of colour production was established, that is to say
the volatilisation of a metal salt in a hotly burning composition, it
was a matter of less difficulty to either eliminate the sulphur, which
was present chiefly as a burnable, or to replace it.
This prohibition, as we have seen, took place in 1894, under Order
in Council 15, and affected the production of coloured fireworks far
less than might have been anticipated. During the period between the
introduction of chlorate of potash and the Order in question, the
development of commercial chemistry had increased greatly the number
of chemicals available in pyrotechny, so that in some few cases it was
found possible to replace the chlorate.
In addition, moreover, most of the leading makers, anticipating
some form of restriction on this admixture, had been for some time
previously seeking substitute colour formulæ, and although it may be
said by some that colours were obtained by the use of chlorate and
sulphur which have not been equalled by subsequent formulæ, yet most
have not only been equalled but improved upon, and the small minority
remaining are an insignificant price to pay for the security and
safety gained in manufacture.
Between the publication of Chertier’s book in 1856 (nearly thirty years
later than his first pamphlet) and the close of the century, several
works on pyrotechny made their appearance, several by Frenchmen:
Tessier, 1859, “Traité Pratique des Feux colorés,” two works in the
Roret encyclopædia series, “Pyrotechnie Civile” and “Pyrotechnie
Militaire,” published 1865, and in 1882, “Traité pratique des Feux
d’Artifice,” by Denisse.
The English works of any value during this period were: “Pyrotechny,”
by Practicus, Brown’s “Practical Firework Making,” and “The
Pyrotechnist’s Treasury,” by Kentish, 1878. Hutstein and Websky’s “Art
of Firework Making,” published at Leipzig in 1878, a book published
under the same title by Oscar Frey about 1885, and “A Theoretical
and Practical Treatise of Civil Pyrotechny,” by Antoni, published
at Trieste in 1893, together with some works on military pyrotechny
published both in Europe and the United States, complete the list.
Some of the military works are of considerable value, but are chiefly
directed to the study of rockets and signals; some, however, are in
the same category as “The Artillerist’s Manual and British Soldier’s
Compendium,” by Captain F. A. Griffiths, R.A., published in 1852. The
section dealing with fireworks in this work might almost be taken as
an attempt to be humorous on the subject. The author quotes in all
seriousness formulæ dating from the days of Bate and Babington, and
knows so little of his subject that he gives instructions for making
the same firework under different names under the impression that
they are distinct units, the information being obviously pillaged
from earlier writers. Generally a study of the above-mentioned works
indicates that the tendency in pyrotechnic compositions has been
in the direction of simplification. During the eighteenth century
the useless ingredients had been in a great measure eliminated. The
“burnables” had been reduced from a long list of alchemistic survivals
to a mere half-dozen or so.
Gums had been reduced practically to shellac alone (the use of gum
arabic as an adhesive is quite distinct), carbons to lampblack and
charcoal, and these with sulphur and sulphides of antimony and arsenic
practically completed the list.
Of the metals the use of pure zinc, copper, and brass has been
discontinued, and the two almost revolutionary additions of magnesium
and aluminium made, the former about 1865 and the latter in 1894.
The date of the introduction of these metals marks almost as great
advances in the art as did the introduction of chlorate of potash. Not
only are they used as spark-producing metals in the same way as are
steel and iron, but they are also used as “burnables,” that is, they
are consumed inside the case; and many of the present-day firework
compositions owe their brilliance to one or other of these metals.
It is, however, in colour compositions that the tendency towards
simplification is most strongly exhibited. In Kentish’s book colour
compositions containing as many as seven or eight ingredients are
common, whereas to-day formulæ containing over four are the exception
rather than the rule.
[Illustration: Roman Candles. This untouched photograph illustrates
the extraordinary brilliance of aluminium compositions. Each
“plume” (200 ft. high) is produced by a single star about ¾ in.
diameter and ¾ in. long. Each line is a microscopic particle of
aluminium.]
The reason for this complexity is not easy to follow, but it may have
been in some measure due to the difficulty of obtaining sufficiently
finely ground chemicals before the days of machine grinding; in some
cases it was found that by melting two of the ingredients together
and allowing the mass to cool they could be ground with greater ease.
Chertier went so far as to melt shellac and salt together, grind them
and remove the salt by dissolving in water. Also by adding a finely
ground chemical of similar action to one only coarsely ground a better
result was obtained.
Whatever may have been the reason, there can be no doubt that, except
for secondary shades, the fewer the chemicals used the more brilliant
will be the resulting fire.