Apart from the activity of inventors in connection with military devices during this period, there was little progress in pyrotechny. Some improvements, however, were made in the compositions used for fixed fires. Hitherto, the combustible for these had been commonly piled upon a piece of tiling, or a flagstone, without being inclosed, and they were set off by a flame applied at the apex. But now the combustible was frequently inclosed in a light case, open at the top. Various experiments were conducted with success in producing colored effects of great brilliancy, in green and red and blue, as well as white. A variety of such fixed fires was the Bengal lights, which, as the name imports, had their origin in India. These were usually formed by piling the combustible on saucers, after which the whole was covered with gum-paper. The lighting was by means of a quick match extending outside the case.
The French chemists were enabled to improve greatly on such illuminating substances as had been known in India. One of the best compositions in the way of a fixed fire was utilized by French astronomers for signaling purposes. This was known as the feu blanc indien. A description of the form in which this was used states that it was contained in a case having a diameter of 10 inches, with a height of 4 inches. But the size might vary, as required by the quality of the composition and the degree of light required. Illumination from the feu blanc was visible at sea for a distance of 40 miles. In the course of a series of experiments, a case of this fire, lighted on the English coast, was seen distinctly by French observers across the Channel.
Efforts were made to duplicate certain fireworks that had gained high repute in Japan. Among these was the "spur" fire, which is so constructed that during the burning scintillations of remarkable beauty are thrown off into the air.
To the astonishment of the investigators, who had analyzed the contents of the spur fire, the result of their efforts was failure. Repeated attempts to duplicate the brilliancy of the spectacle, as shown by the Japanese firework, fell far short of attainment. It was supposed, naturally enough, that the failure was due to some mistake in the preparation of the combustible. It was finally discovered, however, that the secret of the difference lay, not in the inflammable contents, but in the paper wrapper inclosing them. Thus was suggested to workers in the pyrotechnic field the first appreciation of the importance of such paper as may be consumed in connection with the burning of a firework. The chemical constitution of the paper used in making of cases may play an important part in either increasing or lowering the intensity of illumination, especially in instances where pure-color effects are sought.
One very curious device developed during this period was called, by reason of the noise emitted by it while burning, the whistling firework. The composition was three parts of potassium picrate to two parts of niter, or five parts of picrate to one part of niter.
In the construction of the whistling firework, the case is not packed, nor is the mouth shaped. The result is that, on ignition, the rush of flames and gases causes the emission of a shrill, varying note, having an uncanny intensity. The sound rises gradually to a maximum of loudness, which is followed by a rapid diminuendo. These fireworks are now often used in sets of five loaded into a pot, for the garnishing of a rocket.
It is possible that the principle involved in this firework might be adapted to the construction of a projectile for signal purposes, during weather conditions that would render lights invisible. The sound given out might be controlled by adjustment of the case to determine both the pitch and the duration of the note, while the number of repetitions might be systematized as desired, according to the number of whistles loaded with each rocket.
One of the devices produced by the military inventors was fire rain, which was utilized, like others of its class, as an incendiary firework. It derived its name from the fancied resemblance to a shower of rain. It was capable of readily setting fire to besieged buildings when they were covered with inflammable materials, such as shingles, laths, reeds, and the like. The beauty of this particular firework led to its popularity for purposes of entertainment, long after it had been dismissed from attention as an instrument of warfare.
The historical consideration of pyrotechny would be incomplete did it not include a word in passing as to the origin of gas warfare. Humble forms of such warfare may be directly traced to a crude and ancient pyrotechny.
Indian tribes, such as the Tupinamba and Guaranis, of the Brazil littoral and the borders of the Rio Parana, used poisonous gas against their enemies centuries ago. Savage strategy availed itself of such gases in attacks on fortified villages. Here the method, was of the simplest Included among the besieging forces was a body of men equipped with pans containing glowing coals. Supplies of red pepper also were carried. The manner of operation has been described by chroniclers of the Spanish invasion. Often, the whites were sufferers from this species of warfare. Really, the method depended wholly on a favoring wind. Young warriors, ambitious for fame, then sprinkled the pepper liberally on the live embers. When the fumes penetrated to the village of the enemy, their effect, though not usually fatal, was sufficiently noxious to destroy all resistance.
Agi, is the native name of the pepper. Sometimes, it was used by the medicine men of various tribes for the exorcising of evil spirits. We may believe that the effect of the pepper on those present at such rites pointed the way to its employment in warfare.