Page:Willich, A. F. M. - The Domestic Encyclopædia (Vol. 1, 1802).djvu/339

307&#93; BON the phosphoric acid is naturally contained in the bones, and united "with calcareous earth, or whether it is generated by a combination of the vitriolic acid with a certain quantity of lime. As, however, the phosphoric acid has likewise, though in a smaller quantity, been discovered in the gastric juice of animals, there is reason to conclude that it forms one of the elementary constituents of bones. — See Ben- ZOINE. Colouring of Bones. — This pro- cess may be performed eitlier by immersing bones in the common dyeing liquors made of animal and vegetable substances, or staining them without heat, by different metallic solutions. To succeed in the former method, die bones should previously be boiled in a so- lution of alum, and after wards steep- ed in a decoction made of any co- louring substance. Thus, for in- stance, to stain them of a red colour, half a pound of Brazil-wood may be boiled for an hour in a gallon of strong lime-water, in which the bones are suffered to lie till they acquire a proper colour : if diey assume too deep a hue of purple, it will be necessary to plunge them again into a solution of alum, which has the effect of bringing them to a crimson or scar.et shade. By metallic solutions, bones may be easily spotted or variegated. — Thus a soluf'"ii of silver in aqua- fortis, imparts, according to its strength, a brown or black colour j a solution of gold in aqua-regia, or in spirit of salt, a fine purple ; a solution of copper in the acetous acid, a pleasant green ; and solu- tions of the same metal in the vola- tile spirit of ammonia, at first a deep and beautiful blue; but which, on exposing it to the air, BON l3°7 changes into a green, or blueish green. On touching die bone with the two solutions first mentioned, it acquires the desired tint in a few hours, when placed in the open air 5 but in those liquors made widi copper, it should be steeped for at least twenty-four hours, sufficiently to imbibe the colour. In such cases as require immersion for some time, the bone may be variegated, by co- vering those parts which are in- tended to remain white, with wax, or other matter not soluble in the staining liquor. Economical uses of Bones. — Be- side the various toys, and other articles of domestic economy, made of bones, tiiey are extensively use- ful in many of the chemical arts ; for instance, to absorb the sulphur of ferruginous ores for rendering cast-iron malleable ; to form tests and cupels, or vessels for refining gold and silver with lead ; to make glasses and porcelain of a milky colour ; to rectify volatile salts, and empyreumatic oils ; to pro- duce glue, bcc. But the most important and beneficial uses, to which bones maybe rendered sub- servient, are those in rural eco~ nomy. IiiEvelyn's Philosophical Dis- course of the Earth, we meet with a note by Dr. A. Hunter, die editor of a new edition of this treatise, published in 1/7$, from which we shall extract die follow- ing account : Bones are an ex- cellent manure, though not gene- rally known ; they should, how- ever, not be calcined, as their virtue will be dissipated by the fire. A. St. Legek, Esq. had once laid down to grass a large piece of very indifferent lime-stone land, with a crop of corn ; and X 2 from