PYROTECHNY, is, properly speak ing, the science which teaches the ma nagement and application of fire in divers operations ; but in a more limited sense, and as it is commonly used, it refers chiefly to the composition, structure, and use of artificial fire-works. The ingredi ents are, 1. saltpetre, purified for the purpose : 2. sulphur, and 3. charcoal. Gunpowder is likewise used in the com position of fire-works, being first ground, or, as it is technically termed, mealed. Camphor and gutn-henzoin are employed as ingredients in odoriferous fire-works. The proportions of the materials differ very much in different fire-works, and the utmost care and precaution are ne cessary hi the working them to a state fit for use, and then in the mixing. In this work we cannot enter on the subject with a sufficient degree of minuteness to teach the method of making-of fire-works, and shall therefore content ourselves with a brief notice of the proportions of the materials in some of the more com mon, and more interesting articles in use.
The charges for sky-rockets are made of saltpetre, four pounds ; brimstone, one pound ; and charcoal one pound and a half; or by another direction, saltpetre, four pounds ; brimstone, one pound and a half; charcoal, twelve ounces ; and meal powder, two ounces. These pro portions vary again according to the size of the rocket ; in rockets of four ounces, mealed-powder, saltpetre, and charcoal, are used in the proportions of 10 : 2 and 1 ; but in very large rockets the propor tions are, saltpetre, four ; mealed-powder and sulphur, one each. When stars are
wanted, camphor, alcohol, antimony, and other ingredients are required, accord ing as the stars are to be blue, white, &c. In some cases gold and silver rain is re quired; then brass-dust, steel-dust, saw dust, &c. enter into the composition ; hence the varieties may be almost in definite. With respect to colour, sulphur gives a blue, camphor a white or pale colour, saltpetre a clear white yellow, sal-ammoniac a green, antimony a red dish, rosin a copper colour. These ma terials require preparation before they are fit for use ; and before a person can be qualified for the business of fire-work • making, he must understand the method of making the moulds, cases, &c. and be acquainted with the instruments used in the art, their dimensions and materials. To discuss the several topics connected with the business would require a space very much larger than could be afforded in this work ; we shall therefore content ourselves with this notice, referring our reiderShto distinct treatises on the sub -, ject,' which are to be found in the English .
and French language.