There have been many methods used to grind these ingredients to a powder for fire-works, such as large mortars and pestles made of ebony, and other hard woods; but none of these methods have proved so effectual and speedy as the last invention, that of the mealing table. This table is made of elm, with a rim round its edge four or five inches high; and at the narrow end 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 a copper shovel, you may sweep all clean out at the slider. When you are going to meal a quantity of powder, observe not to put too much on the table at once; but when you have put in a good proportion, take a muller and rub it therewith till all the grains are broken; sift 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 gunpowder, only the muller must be made of ebony, for these ingredients being harder than powder, would stick in the grain of the elm and be very difficult to grind; and as the brimstone is apt to stick and clog 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. _Spur Fire._ This fire is the most beautiful of any composition yet known. As it requires great trouble to bring it to perfection, particular care must be paid to the following instructions. They are made generally in cases about six inches long, but not driven very hard. CHARGE. lb. oz. CHARGE. lb. oz. Saltpetre 4 0 } { Saltpetre 1 0 Sulphur 2 0 } or { Sulphur 0 8 Lamp-black 1 8 } { Lamp-black 4 quarts. This composition is very difficult to mix. The saltpetre and brimstone must be first sifted together, and then put into a marble mortar, and the lamp-black with them, which you work down by degrees with a wooden pestle, till all the ingredients appear of one colour, which will be something greyish, but very near black; then drive a little into a case for trial, and fire it in a dark place; and if the sparks, which are called stars or pinks, come out in clusters, and afterwards spread well without any other sparks, it is a sign of its being good, otherwise, not; for if any drossy sparks appear, and the stars not full, it is then not mixed enough; but if the pinks are very small, and soon break, it is a sign that you have rubbed it too much.