The antimony, which enters into the composition of many fire-works, is not to be understood to be the metallic, or regulus of, antimony, unless so expressed; but the crude antimony of the shops. Crude antimony is a combination of antimony and sulphur, and is usually met with in fine powder. That both antimony and its sulphuret have a powerful effect in modifying the flame of gunpowder, and all compositions, in which nitre and inflammable substances form a part, is evident from the many cases, in which it is employed, and from the effects that thereby result.
The different substances in any inflammable compound, intended to produce particular colours, should be so mixed, as that, from a knowledge of the proportions which produce such colours, the effect may be retained, even when it is mixed with other bodies. For this reason, the artist should know the different effect of each ingredient. Some may show themselves in the flame, some in sparks, some in stars, others in fire-rain, and the like, as the case may be. Antimony, for instance, produces a reddish flame, if it be in a proper proportion, and not altered by the presence of other substances. Hence, when antimony is mixed with nitre, the flame will be more or less a whitish-green.
This modification, or change in the appearance of flame, is apparent in certain compounds, of which antimony constitutes a part. Thus, antimony is used in the preparation of the common rocket stars, in drove stars, in the fixed pointed stars, in some of the gold and silver rains, in the slow and dead fire for wheels, in tourbillons for crowns or globes, in the composition of serpents, lances for illumination, Bengal lights, and many other kinds of fire-works. According to Adye, (Pocket Gunner,) it enters into the composition of carcasses, Chinese lights, &c.
When it is as one to sixteen of nitre, the gunpowder being as four, and the sulphur, eight, the composition will produce a white flame; but when it is in the proportion of eight to sixteen of nitre, without any addition, the flame will be blue. By substituting, in its place, eight of amber to sixteen of nitre, with sixteen of sulphur, and eight of meal powder, this change will produce a yellow flame. It is obvious, however, that these and similar changes are owing to the proportions, as well as to the substances used.
Antimony, in the state of a sulphuret, when mixed with chlorate of potassa, &c. will form detonating compounds.
Antimony is a grayish-white metal, more or less brilliant and laminated. It is brittle, and may be easily reduced to powder. It melts at a red heat, and evaporates at a higher temperature: on cooling, it crystallizes. It undergoes no change by exposure to the air, except the loss of its lustre. When steam is made to pass over ignited antimony, the decomposition of the water is so rapid, as to produce a violent detonation. At a white heat, it burns, and forms a white coloured oxide, called the argentine flowers of antimony. Its oxides are various, some of which, possessing acid properties, are called acids. The protoxide is gray, the antimonious acid, white, and antimonic acid, of a straw colour. The crocus of antimony, and the glass of antimony are oxides of this metal, but in particular states of combination. It unites with several of the acids. Its oxide, with tartaric acid, and tartrate of potassa, forms tartar emetic. With chlorine, it constitutes the butter of antimony.
The artificial sulphuret may be formed, by melting sulphur and antimony together. The native sulphuret is almost the only ore of antimony, and is the mineral from which the regulus is obtained. It unites with the metals, forming alloys of different kinds.
Sect. XXXVII. Of Carbonate of Potassa.
Potassa, either pure or carbonated, retards the progress of combustion; and, therefore, may prevent, according to the proportion employed, the action of combustible bodies on nitre. Combustion may be retarded by using those substances, which are not in themselves inflammable, and which, if used in too large a quantity, would effectually prevent it. Clay, wood ashes, &c. as in the blind fuse, act on this principle; and serve, also, in particular cases, to produce that succession of explosions, which renders the effect of some fire-works, more grand and impressive. Rope, soaked in a solution of saltpetre and dried, would burn rapidly, were it not for the after immersion in potash ley, or urine, either of which acts by retarding the progress of combustion. The same thing may be said of other bodies, the use of which will claim our attention hereafter. Potassa, although not generally used for the purposes mentioned, as it is apt to deliquesce, or absorb water, and thus destroy the effect altogether, may be more advantageously employed in a liquid state, as in the preparation of slow match in the way stated under that head. But as match rope is now generally superseded by the port-fire, as a more certain method of firing cannon, it would be unnecessary, as it is irrelevant, to enlarge on this head. The use, also, of the priming fuse, which conveys the fire to the powder in the gun, with certainty and with rapidity, is an improvement of no small moment.