The use of the above characters is, that by the help of them, the different receipts may be contracted to so small a compass, that they may all be contained in one leaf of a pocket book, which is much less than any table that has yet been invented. These signs are also very convenient for those who travel.
How to meal Gun-powder, Brimstone, and Charcoal.
There have been many methods used to grind these ingredients to a powder for fireworks, such as large mortars and pestles, made of ebony, and other hard wood; likewise horizontal mills with brass barrels; but none of these methods has proved so effectual and speedy as the last invention, that of the mealing table, which is represented in [Plate 1.] Fig. 1. This table it made of elm, with a rim round it’s edge, four or five inches high; and at the narrow end, A, is a slider, which runs in a groove and forms part of the rim; so that when you have taken out of the table, as much powder as you conveniently can, with the copper shovel [Fig. 2.] you may sweep all clean out at the slider A. When you are going to meal a quantity of powder, observe not to put too much in the table at once; but when you have put in a good proportion, take the muller [Fig. 3.] and rub it therewith till all the grains are broke, then fearce it, in a lawn sieve that has a receiver and top to it; and that which does not pass through the sieve, return again to the table and grind it more, till you have brought it all fine enough to go through the sieve. Brimstone and charcoal are ground in the same manner as gun-powder, only the muller must be made of ebony, for these ingredients being harder than powder, would stick in the grain of elm, and be very difficult to grind; and as the brimstone is apt to stick and clod to the table, it would be best to keep one for that purpose only, by which means you will always have your brimstone clean and well ground.
To prepare Cast-Iron for Gerbes, White Fountains, and Chinese Fire.
Cast-iron being of so hard a nature, as not to be cut by a file, we are obliged to make use of the following method to reduce it into grains, though somewhat difficult to perform; but if we consider what beautiful sparks this sort of iron yields, no pains should be spared to granulate such an essential material, to do which you must proceed thus: get at an iron foundry some thin pieces of iron, such as generally runs over the moulds, at the time of casting: then have a square block made of cast iron, and a square hammer of the same metal, about four pound weight; then, having covered the floor with cloth, or something to catch the beatings, lay the thin pieces of iron on the block, and beat them thereon with the hammer, till you have reduced them into small grains, which afterwards searce with a very fine sieve, in order to separate from them the fine dust, which is sometimes used in small cases of brilliant fire, instead of steel dust; and when you have got out all the dust, sift what remains with a sieve a little larger, and so on with sieves of different sizes, till the iron will pass through about the bigness of small bird shot: your iron being thus beat and sifted, put each sort into wooden boxes or oiled paper, to keep it from getting rust. When you use any of this iron, observe that you make a difference in its size, in proportion to the cases for which the charge is intended; for the coarse sort of it is only designed for very large gerbes, of six or eight pound weight.
Charges for Sky-Rockets, &c.
For Rockets of Four Ounces.
Mealed powder one pound four ounces, saltpetre four ounces, and charcoal two ounces.
For Rockets of Eight Ounces.
I. Meal powder one pound, saltpetre four ounces, brimstone three ounces, and charcoal one ounce and a half.