Nitrate

(nit rat.) (Chem.) A combination of nitric acid with a base. For the most part they crystallize readily, they are all soluble in water, and are generally neutral to test-paper. When heated they readily decompose, evolving for the most part a mixture of oxygen and oxides of nitrogen; heated with combustible bodies they deflagrate violently, and sometimes explode. The following are the most important nitrates. N. of Culciun. A salt which is formed naturally in many parts of the world, and artificially in some countries, by imitating the conditious of nature. When heaps of decomposing animal and vegetable matter, mixed with clay, chalk, ashes, ., and moistened with urine, soapsuds, ., are exposed to the air for some years, decomposition takes place, and the nitrogenous matters oxidize to nitric acid, which, uniting with the calcium of the chalk, forms N. of calcium. The solution from the lixiviated ma is mixed with a pota ium salt to decompose the calcium salt, and evaporated down, when N. of pota ium crystallizes out. These beds are called artificial nitre beds or saltpetre plantations, and are largely employed in Europe.- N. of Pota ium, called also nitre and saltpetre (KO.NO₂). A white inodorous salt of a cooling bitter taste, crystallizing in long six - sided pri sins which are anhydrous and very soluble in water, and readily crystallized therefrom. N. of pota ium melts below a red-heat without further change, solidifying on cooling to a hard white ma known in commerce as sal-prunelle. At a red-heat oxygen is given off, N. of pota ium being left, and if the heat is continued nitrogen is evolved with the oxygen. When heated with combustible substances deflagration takes place; on this property its use in the manufacture of gunpowder and pyrotechnic mixtures depends. N. of pota ium is found as a natural product in many parts of the world, where its formation is still going on. It is also prepared in enormous quantities by decomposing N. of sodium with carbonate of pota ium or caustic potash, when a double decomposition takes place, and N. of pota ium is separated by crystallizing.-N. of Silver (AgO NO3), known also as lunar caustic, lapis infernal is. A salt crystallizing in colorle tri metric crystals very soluble in cold water. When mixed with organic matter and exposed to light, reduction of silver to the metallic state takes place. This property is taken advantage of in photography. N. of silver forms insoluble compounds with many kinds of animal matter, and is then gradually reduced to the state of metal, with oxidation of the organic substance; on this account N. of silver is used as a caustic, as it rapidly destroys organization and vitality when applied to the moist surface of the body.- N. of Sodium, called also Chili saltpetre, Cubic nitre (NaO.NOg). A salt crystallizing in obtuse rhombohedrons which closely approach cubes, hence the name cubic nitre. It is deliquescent in moist air, and di olves readily in water; it behaves with heat in a similar manner to N. of pota ium. Owing to its low price, it is largely used in the manufacture of saltpetre and nitre, and also for manure. [s. 648]