Luminous or light balls are sometimes made of the following compositions.
Composition for Luminous Balls.
| 1. | Sulphur | 6 oz. |
| Antimony | 2 — | |
| Saltpetre | 4 — | |
| Rosin | 4 — | |
| Charcoal | 4 — | |
| 2. | Saltpetre | 2 oz. |
| Rosin | 2 — | |
| Charcoal | 2 — | |
| Antimony | 1 — | |
| Sulphur | 1 — | |
| Pitch | 1 — |
In the formation of luminous, or light balls, whatever may be the composition, we may remark, that the only ingredients which appear to be essentially necessary are nitrate of potassa and inflammable substances. In some preparations, antimony is used, for the same reason as in the Bengal lights. Rosin, pitch, and charcoal are all inflammable; and sulphur, although it takes fire more instantaneously than these, enters into the composition of such fires more on account of its flame than any other.
As a general rule for the preparation of carcass composition, the following particulars must be attended to. After melting the pitch, turpentine, rosin, and sulphur, add the tallow and camphor, and then the nitre and charcoal, in powder. They are then to be stirred, and mixed intimately. Care must be taken to regulate the fire, and prevent the composition taking fire. After the kettle is withdrawn from the fire, the gunpowder is then gently added, and stirred with a stick or spatula. The kettle is then again put over the fire, and afterwards withdrawn. Tow is now added in small quantities at a time, stirring the mixture well that it may be thoroughly incorporated.
The preparation of the carcass, or fire-ball, is as follows; observing, that, if it is a carcass, the iron-frame must be first placed in the sack. Four cords are taken, each four lines in diameter, four feet long for the calibers of 10 and 12 inches, but only 3 feet for the calibers of 8 inches.
The middle of these four cords are laid one upon the other in the form of an eight-pointed star. Each end of the ropes is then fixed to a nail, and a bottom is formed, similar to basket-work, by interlacing a cord, two lines in diameter, three or four times round the central point. The small cord is then tied with a knot, and the bottom of the basket completed, by tying the four large cords together with four half knots. The bottom of the sack, containing the iron carcass, or of an empty sack, if a fire-ball is to be made, is placed upon the middle of this, and the filling performed in the following manner, namely: A sufficient quantity of the composition is taken from the kettle to fill the empty carcass, or sack, three or four inches high; a few loaded grenades, with the fuse down, or a howitz placed in the same way, are laid upon this first layer. The filling is continued to the top, putting the composition and grenades, in alternate layers. When it is done, the sack is tied with twine. In order to tie up the fire-ball in its cord net, the cords are raised from their nails, over the sack, and tied in such a way as to suspend it about the height of a man's head, and to permit it to be easily turned round. An artificer fixes the end of a small cord to one of the larger ones, at the distance of 11/2 inches from the bottom; he makes a half knot upon this, and carries the small cord round to the others, to which he ties it in the same way, forming a spiral round the ball. The large cords are kept regularly stretched in such a way, that each turn of the spiral may be 11/2 inches from that beneath it. When the spiral has reached the top of the ball, he unites the small cord, called the traverse, with the ends of the four others, called uprights. He divides the latter into two parcels, and forms a loop of them, through which a lever may be passed for the convenience of carrying it. At two or three inches from the upper end, and upon two sides, diametrically opposite to each other, two pins of hard dry wood, well greased, are driven in. These pins are 6 inches in length, one in diameter at the head, and half an inch at the point. They must be inclined in such a way, as to meet in the axis of the fire ball, at about half its height.
The carcass or fire-ball, when finished, is dipped into the following composition:
Composition of Pitch for Fire-Balls.