Having thus given some of the modes, usually adopted to render wood incombustible, or to prevent its taking fire so instantaneously, we purpose to add some remarks respecting the processes for colouring it. An excellent preservation against moisture, which communicates a colour at the same time, is formed of 12 lbs of rosin, 3 lbs of sulphur, and 12 pints of whale oil, melted and mixed with a sufficient quantity of red or yellow ochre, and applied by means of a brush. Pulverized black lead may be substituted for the ochre. Several coats of this mixture may be put on, allowing each coat to dry before another is applied. This composition is particularly well adapted for wheel work, &c. and for aquatic fire-works. Chaptal advises, for the same purpose, a mixture of equal parts of white turpentine, bees' wax, and maltha, or, in the place of maltha, coal tar. Wood, covered with three coats of this composition, and immersed for two years in water, was found to be quite dry. It would be well, however, to cover it with some of the preparation, to render wood incombustible. With respect to the staining of wood of various colours, several preparations may be used. To communicate a green colour, a hot solution of acetate of copper may be used; or verdigris, alum, and vinegar, boiled together. A decoction of brazil wood, with alum and cream of tartar, will impart a red; indigo, dissolved in sulphuric acid, (liquid blue dye), a blue; a decoction of logwood, nut-galls, and copperas, a black; a solution of dragon's blood, or of alkanet wood, in turpentine, a mahogany colour, &c. The imitation of bronze on wood may be effected, by covering it first with isinglass size, then suffering it to dry, and putting on a coat of oil gold size, and covering it with bronze powder, a preparation sold for that purpose. A solution of aloes in spirits, which communicates a greenish-black, is a great preservative of wood against worms. M. Ollivier (_Archives des Découvertes_, v, p. 386) has given a variety of recipes for imitating bronze, stone, &c. He recommends the following for the imitation of ancient bronze, which may be applied to wood-work. Melt together 150 lbs of fine sand, 170 lbs of lead ore, (Galena), and 30 lbs of manganese, and add one-sixth part of brass. This compound is then pulverized. It is applied on the usual ground. _Black earth_, as it is called, made of green earth, oxide of manganese, oxide of iron, and oxide of copper, is also recommended for covering wood-work. The composition for _imitation marble_, is 1 part of green earth, 1/2 a part of sand, and 1/8th of a part of bol. armen. By adding 1/14th part of _yellow burnt copper_, the colour will approach to green. The same composition, with 1/16th part of copper, and 1/32d iron, will give a black. _Sec. VII. Of the formation of Rocket, and other Cases._