"These three articles being mixed, you will put them in a wooden bowl, and moisten them with linseed oil, until you find the composition (being pressed well) is sufficiently hard." It may be sufficient to observe, that the present improved process of making port-fires is preferable. (See _Port-fires_.) _Sec. XII. Of Pasteboard, and its Uses._ The pasteboard, used in pyrotechny, is made of fine white paper, by joining together five, and sometimes six, seven, and eight sheets of paper. That which is generally employed, is made of five sheets, and the other descriptions are employed for large cases. Sized paper is preferable, having more firmness than the other. Pasteboard is made in the following way: A paste of flour is first prepared with hot water, and passed through a hair sieve, to separate the lumps. A sheet of paper is stretched upon a table, and covered, by means of a brush, with paste, and a sheet is then laid over it. This is compressed, and another coat of paste applied; then another sheet, then paste, and the number is added according to the thickness required. After five or more sheets are thus pasted together, a dry sheet is laid over, and the operation is repeated, till five more are joined. Then a dry sheet is put on, and the pasting is renewed. By this means, every five sheets are joined together, and the sheet, thus formed, is kept apart from the rest, by the dry sheet. A pile of pasteboard, consisting of some hundred sheets, may be made in this manner at one time. They are then put into a press for the space of five or six hours, by which they become firmly united, and all the extraneous paste is pressed out. When a press cannot be had, they may be put between boards, and heavy weights laid on. The pasteboard is then hung up in the air to dry, and again submitted to the press, to remove any inequalities, and to make it smooth. When glazed paper is used for making pasteboard, we may employ, alternately, a sheet of brown paper. It is better, however, to use more of the glazed paper, than of the brown paper. Pasteboard of three thicknesses will be sufficient for most purposes. It is this kind, which is used for the heads of rockets. Several kinds of paper, however, are used in fire-works. For small preparations, common white paper is sufficient. For port-fire cases, the common brown paper; for the joints, guarding places from fire, and covering tubes of communication, any kind of gray paper; and for covering marrons, the most indifferent kind may be used. Cartridge paper, as known by that name, may be used for a variety of purposes. Paper may be rendered incombustible, or nearly so, by soaking it repeatedly in a strong solution of alum. In the _Literary Journal_ of 1785, of Petersburg, there is a discovery mentioned of a kind of pasteboard, which neither fire can consume, nor water soften. It appears that alumina, and its salt (alum) were used in this preparation.