The Chinese are in possession of several processes, as well for making, as for ornamenting paper. Their silver paper, which is sometimes put on their fire-works, is variously figured. The art is very simple. Two scruples of glue, and one scruple of alum, are dissolved in a pint of water. This is evaporated, and put on the paper, where they want it, and finally pulverized silvery talc (a magnesian stone) is sifted over it. It is then exposed to the sun, and the extraneous talc is brushed off. The glue, it is obvious, causes the talc to adhere.
The Abbé Raynal (Histoire Philosophique des deux Indes t. iii, p. 225) has some interesting facts respecting Chinese paper. Some useful remarks on paper hangings, paper for decorations, tapestry paper, &c. may be found in the Journal de Paris, 1785, the Lycée des Arts 1795, and the Encyclopedie Method. Arts et Metiers, t. iv, p. 393. On the formation of paper vases, in imitation of Japan vases, consult the Dictionnaire de l'Industrie, article vases. The different patents, respecting paper, may be seen in the British Repertory of Arts, and the manufacture of paper generally, in Rees's Cyclopedia, and the Artist's Manual. The American improvements are noticed in the latter. Beckman (History of Inventions) has a variety of remarks on the same subject; and, in his article on paper hangings, &c. vol. ii, p. 161, says, that artists employed the silver-coloured glimmer (isinglass) for the covering of paper, and that the nuns of Reichtinstein ornamented with it, the images, which they made; as the nuns in France, and other catholic countries, ornamented their agni Dei, by strewing over them a shining kind of talc.
The quality of the paste, which is employed in making pasteboard, ought to be attended to. The flour should be of rye, and well boiled, after mixing it uniformly with cold water. Strong bookbinder's paste has the addition of a fourth, fifth, or sixth of the weight of the flour, of powdered alum. The patent paste is prepared by extracting starch from potatoes, in the usual manner, by means of cold water, and mixing it with mashed potatoes, after they have been boiled, and boiling the whole in water.
The Japanese cement, or rice-glue, may be advantageously used in many cases. It is formed by mixing rice flour intimately with cold water, and then boiling it very gently. It is beautifully white, and dries almost transparent. We are told, that it is preferable, in every respect, to the paste made with flour; and its strength is such, that paper, pasted together with it, will sooner separate in their own substance than at the joining.
The Chinese, to prevent accidents, and in order that they may fire their works without injury, and particularly their cases which are charged with brilliant fire, have a process, for preparing a paste of a different kind. With the exception of the clay, the same substances have been employed elsewhere for the like purpose. It consists of one pound of rye flour, boiled in water; to which is added, a small handful of common salt, the whole being thickened with finely pulverized white clay. The pasteboard, we are informed, which is made with this paste, is not only very solid, but not so susceptible of inflammation, as that prepared in the usual way.
A Chinese paste is announced in the Bulletin de la Société d'Encouragement, 1815, which is very economical, and used with success. It is made by mixing ten pounds of bullock's blood, with one pound of quicklime, and occasionally flour.
Sec. XIII. Of the Pulverization of Substances.
Various substances are employed either in grain, laminæ, filings, or impalpable powder. When treating of nitre, sulphur, and charcoal, and other bodies, we mentioned the processes for reducing them to powder. It will be sufficient here to remark, that cannon powder, when it is converted into fine powder, takes the name of meal-powder; the conversion being effected, by beating it in a leather sack, already described, by rolling it upon the mealing-table, or by the action of a wooden pestle in a mortar. It is then passed through a fine sieve. The sack is said to be a preferable mode, as nearly the whole of it becomes pulverized. Saltpetre, sulphur, charcoal, antimony, &c. may be reduced to powder in a mortar of cast-iron, marble, or wood. The best method of pulverizing saltpetre is given under that article, which consists in boiling it in a copper, and stirring it continually at the end of the process. The best mode of pulverizing, or bringing cast-iron to a state of fineness, is mentioned in the article on Iron. Some of the metals, as iron, zinc, the alloy of copper and zinc, (brass,) &c. are brought to a sufficient fineness by the file. The filings, if so required, may be afterwards sifted. Zinc, when in small pieces, may be pulverized, by means of a steel mortar and pestle. It may be granulated, by suffering it to run, when melted, through an iron cullender into water. For the pulverization of camphor, see [that article.]