As we are not acquainted with any trustworthy or practical account of the method of preparing gelatine, we have been at some pains to procure the following information respecting its manufacture. Ordinary gelatines are made from those pieces of skins which are cut off by the tanner as unfit for making leather, in consequence of thickness. The best description is prepared from the skins of calves' heads; these are separated from the whole skins after they have passed through the process of liming, to remove the hair from them. The skins are next well washed, to get rid of the lime, and all the pieces of flesh and fat are carefully cut out; some manufacturers soak them for a short time in a dilute solution of muriatic acid, to remove any remaining portion of lime; but this practice is both injurious and unprofitable. The acid forms with the lime chloride of calcium which, if it is not carefully removed by washing, is boiled up with the skins, and being soluble, remains in the gelatine; a portion of the skins is also dissolved by the acid, and is thrown away in the water employed in washing them, which thus occasion a loss in weight. In some cases the skins are boiled whole, in others they are cut into small pieces, or even reduced to a pulp by a macine especially constructed for the purpose. If the skins are cut into fine pieces, instead of being put into the boiler whole, the gelatine will be better; that is, it will be of a lighter colour; and the process is more economical, as one half the time will be saved in the boiling, and much less heat and fuel required. As the gelatine is darkened by prolonged boiling, the reduction of the skins to a pulp is a point of very great importance in the manufacture of gelatine- so much so, that Mr. Swinburne has obtained a patent for this method of preparation. The skins are boiled with water, in the proportion of about one gallon of water to seven pounds of skin; a small quantity of common salt is added to preserve the gelatine. After it has boiled for about twelve hours, it is strained and clarified with white of eggs, and then run upon glass plates; as soon as it is solid, it is cut into slices and laid upon nets to dry, in a room heated to a temperature of about 80 [degrees]. If the room is not heated, the surface of the gelatine becomes covered with small air-bubbles; when the gelatine is dry, it is cut by a machine in the same manner as isinglass. The size of the glass plates varies according to the fancy of the manufacturer. The ordinary size is fifteen by eighteen inches; but in some cases they are three feet square; the plates or slices of gelatine are generally about fifteen inches long by three wide. Though the skin of the head of the calf only is used for making gelatine, the whole of the skins both of the calf and ox are perfectly adapted for the purpose, but are not used, a they are much more valuable for conversion into leather. In some cases, especially in warm weather, the skins used are somewhat decomposed, but this is not generally the case. This condition, although removed to some extent by repeated washings, cannot be entirely remedied; hence gelatine made from such damaged skins will always retain a smell and taste more or less disagreeable. French gelatine is usually much whiter than English; this is owing principally to the calves being killed in France much younger than in this country. Gelatine is likewise prepared from the bones of the ox and the sheep. It is obtained by boiling bones in water under pressure. It is more readily procured by employing bones which have been previously digested in hydrochloric acid to extract the phosphate of lime. In this way a nutritious soup is prepared in Paris for the hospitals and other pauper habitations. Gelatine has been extracted from antediluvian bones. A soup was prepared from the bones of the great mastodon by a pr‚fet of one of the departments of France. ,-Pereira.,