The choaker is nothing more than a contrivance, usually made of rope, by which the closing of the end of the rocket is effected, so as to form a kind of cup or mouth. _Sec. IX. Of the Table and Sack for mealing Gunpowder._ This table may be either square or an octagon, and made of hard wood. There is a rim, a few inches high, raised round it, and a gutter at one end to allow the powder to pass out, when the operation is finished. See plate, fig. 7 and 8. This mode of mealing powder is by no means to be preferred. (See _Gunpowder_.) A sack is also used for crushing powder. It should be made of strong elastic leather, and sewed together in such a manner as to prevent the impalpable powder from passing through its seams. They are of an oblong shape, and contain from 20 to 25 pounds. Fifteen pounds are generally put in at a time. This method of crushing powder is preferred, as it is less liable to accidents. It is hardly necessary to add, that the bag is beaten with a cylindrical stick. _Sec. X. Of Sieves._ There are several kinds of sieve. The common sieve has neither a cover nor a receiver, and may be either formed of horse hair, or of brass or copper wire. It is necessary to have some sieves of a finer kind. For this purpose, silk and gauze are generally used. The cover is merely leather, fixed in a frame, which fits on the top. The receiver is formed nearly in the same manner, having a skin stretched over a frame, which fits on the under part of the sieve. _Sec. XI. Of the Paper Press._ A press, for the purpose of pressing paper, is formed of two pieces of wood, which are brought together by means of one, or several screws. This press is sometimes, though seldom, used. If pasteboard is made, when it cannot be had ready prepared, then the press is actually necessary. The intention is to unite the several sheets, which have been pasted, by using the pressure of the screw, and to remove any extraneous paste, so that the paper may have no inequalities on its surface. In lieu of the screw-press, heavy weights laid on the paper for several hours, will answer the same purpose. CHAPTER II. _Preliminary operations in the preparation of fire-works, and observations on the preservation of gunpowder, and sundry manipulations._ _Sec. I. Of the Workshop._ We have already noticed the principal furniture of a laboratory, and, therefore, can add nothing new on this head. There are, however, some utensils employed for particular works, which we may here describe.