PHOSPHORESCENCE is the proper ty which certain bodies possess, of be coming luminous without undergoing combustion, as, when we rub or heat them, or in consequence of the action of the living principle, or of decomposition. Two pieces of quartz emit light on being rubbed together. Light is seen in break ing lumps of sugar. A variety of blonde (sulphuret of zinc), on being scratched with a knife, emits a fine yellow light. PHOSPHORIC ACID is present in the solid parts of all animals, and displayed especially in the urine. By Barry's ex periments, it appeared in all pharmaceu tical extracts, and it exists in all articles of food, and, as phosphate of lime, exists in bones, and in all vegetables. It ap pears in all the substances of animals, and their products. In the mineral kingdom, it is found in lead and iron, in silex, in calcareous earths, and in union with lime, sometimes in whole mountains, as in Spain and Hungary. The acid is formed by the combustion of phosphorus, and, so to speak, is an oxide. But it is also made
by distilling phosphorus with nitric acid, or with sulphuric acid or chlorine. It is soluble in water, which takes tip 1.687 with increase of temperature. Distilled with charcoal or inflammables, they ab stract its oxygen, and it returns to the state of phosphorus.
Phosphoric acid and barytes form a salt, which, with great heat, forms gray enamel.
Phosphoric acid and lime, oriphosphate of lime, is insoluble in water till calcined. It absorbs grease, and serves to polish stones and metallic surfaces. (See PHOS PHORITE Phosphates of potash and soda are made, and the latter is used, as a purga tive salt, having no flavor ; also iu assays, and in soldering.
Phosphate of ammonia abounds in urine, and much employed as a flux, and in coloring glass.
Other phosphates are formed, but not applied to any purpose.