Benzoin.
8. Benzoin.—Benzoin, or as it is vulgarly called Benjamin, is a resinous matter obtained from the tree called Benzoin, and is brought from different parts of the Indies, where it is found of various kinds, and of different colours; the best is that which is full of white spots and is easily broken. It is used in odoriferous fire-works, but prior to which it must be reduced to a fine powder, which may be effected by the following method:—put about three or four ounces of Benzoin grossly pounded into a deep and narrow earthen pot, and cover the pot over with a cone of thick paper, which tie closely round the edge, then place the pot over the fire and apply a moderate heat; after the interval of an hour take off the cone, and you will find some flower sticking to the under-side of it; or in the language of chemistry, the acid is sublimed and is deposited on the paper; the cone must be returned to the pot, and the operation continued till the flower appears very white and fine.
The acid which is frequently used may be obtained by digesting Benzoin in sulphuric acid, and by this it is obtained much purer and in finer crystals than by any other method.
On this article we deem it requisite to give the above information; but to the private practitioner, it will be more eligible to purchase it ready prepared.
[SECTION III.]
Apparatus.
In the practical part of Pyrotechny, the constructing and due proportioning of the moulds is a very material consideration, for on these the goodness of the article depends nearly as much as on the purity of the ingredients. They consist chiefly of solid and hollow cylinders made either of wood or metal; those that are hollow are called moulds, and those that are solid formers; both are used in the construction of rockets; similar cylinders either of wood or metal are used for ramming down the composition; a machine for contracting the aperture of the cases, the operation of which is called choaking; another for boring them after they are filled; and a simple apparatus for grinding the materials previous to the cases being filled, as well as others of less importance, which we shall choose rather to describe as their assistance is required.
We shall begin the important Apparatus with describing those which come most immediately into use.