CHAPTER VIII

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.

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.