83. TO PRODUCE FLAME OF VARIOUS COLOURS.--This may be effected by mixing certain substances with burning alcohol, or by applying them with the point of a pen-knife, to the wick of a burning lamp or candle. Thus a beautiful rose or carmine coloured flame may be produced by muriate of strontia: this is prepared by dissolving carbonate of strontia in muriatic acid, and evaporating it to dryness. The preparation for an orange colour, is muriate of lime; (a solution of marble in muriatic acid, evaporated to crystallization) which should be exposed to a moderate heat till it is deprived of its water of crystallization and falls to powder. A fine green tinge is produced by acetate of copper, or boracic acid; which last is procured by adding sulphuric acid to a solution of borate of soda (in hot water) till it has a sensibly acid taste; as it cools, the boracic acid is deposited in crystals on the sides of the vessel. Camphor gives to flame a blue colour; and nitrate of strontia (prepared the same as the muriate) a purple. A brilliant yellow may also be produced by muriate of soda. Any of these preparations being reduced to powder, may be ignited with three or four times their weight of alcohol, which should be previously warmed; and if the vessel that contains it be kept heated also, the combustion will be the more brilliant. 84. TO MAKE SKY-ROCKETS AND FIRE WHEELS.--Grind and mix together, (dry) one pound of gun powder, two ounces of sulphur, two ounces of nitrate of potass, and four ounces of newly burnt charcoal. Then make several strong paper cases or cartridges, by wrapping some strong paper (being moistened with paste,) fifteen or twenty times round a mould made of wood, which may be one inch in diameter, and ten inches in length. One end of this mould must be made smaller, being only one fourth of an inch in diameter for the space of an inch of its length. The paper must be drawn up close round this neck, and strongly bound with twine, being thus brought to a shape similar to the neck of a phial. This neck is called the choke of the cartridge. Take the paper from the mould, and proceed in the same manner with another. When a sufficient number of cartridges are thus made and dry, place one of them in a socket which it will fill up closely, and then fill the cartridge with the above described compound powder, which must be thrown into the cartridge in small quantities, and each several quantity must be rammed or beat down very hard, with a suitable sized rammer and mallet. In filling the cartridge, small quantities of any of the flame-colouring preparations, described in the preceding article, may be added occasionally. When the cartridge is nearly full, some small balls of cotton, dipped in spirits of turpentine, may be added, to produce the appearance called stars.--These also, may have some muriate of strontia, or boracic acid strewed on them. Then place a circular piece of thick paste board on the materials in the