| Saltpetre, | 16 | oz. |
| Sulphur, | 8 | — |
| Meal powder, | 4 | — |
| Antimony, | 1 | — |
This is the formula, given by Morel; but the formulæ of Bigot are in some respects different, namely:
| 1. | Saltpetre, | 16 | oz. |
| Sulphur, | 8 | — | |
| Meal powder, | 5 | — | |
| Antimony, | 2 | — | |
| 2. | Saltpetre, | 19¾ | — |
| Sulphur, | 8⅝ | — | |
| Antimony, | 2 | — | |
| Charcoal, | 0⅝ | — |
Serpent stars are of two kinds. The one is intended as the furniture for rockets, &c. and the other, when moulded, to be employed in the Roman candles.
When required to be moulded, or made into cakes, the composition is mixed with gum and brandy, into a paste, which is spread upon a table, having previously covered the table with meal powder. Small cubical or other shaped pieces are cut out, sprinkled with meal powder, and dried in the shade. The meal powder serves as a priming, so that they may all take fire at the same time. The composition may be formed into balls.
Serpent stars, being designed to produce a combined effect, it appears, that, while charcoal, (and, in some instances, the sulphur, according to the formula, but more especially the charcoal), imparts the serpentlike appearance, the antimony, in its turn, diversifies the flame by giving to it an asteroid character. The antimony, used in these compositions, is not the regulus, but the crude, or common sulphuret. Metallic antimony, however, would produce the effect in a greater degree: but as sulphur enters into their composition, and also into the crude antimony, there would be but little, if any, advantage, gained in the use of the regulus.
Besides the ordinary products of the combustion of gunpowder, or similar products, by employing nitre, charcoal, and sulphur, the antimony, by its combustion, would be changed into an oxide, or, if the combustion is sufficiently rapid, and the quantity of oxygen absorbed proportionate thereto, it would form the antimonic acid. That it is oxidized, however, and that during its oxidizement, the appearance we have mentioned takes place, there can be no doubt.
Sec. V. Of Whirling Serpents.
Serpents, prepared in the following manner, have a peculiar effect, by which they are characterized. They form in the air a kind of whirling sun; and, as they revolve by reason of their fire issuing out at the opposite sides of their extremities, they resemble the sun turning on its axis.