The London medical dictionary: including, under distinct heads, every branch of medicine, viz. anatomy, physiology, and pathology, the practice of physic and surgery, therapeutics, and materia medica ; with whatever relates to medicine in natural philosophy, chemistry, and natural history (Volume 2).

  • Parr, Bartholomew, 1750-1810.
Date:
1819
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Licence: Public Domain Mark

Credit: The London medical dictionary: including, under distinct heads, every branch of medicine, viz. anatomy, physiology, and pathology, the practice of physic and surgery, therapeutics, and materia medica ; with whatever relates to medicine in natural philosophy, chemistry, and natural history (Volume 2). Source: Wellcome Collection.

Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)

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    ' ' icd by the vegfctable fixed alkali with the nitrous It has a sharp though cooling taste, is soluble in 1 times its weight of temperate, and an equal iitof boiling, water. The crystals are octagonal piibiiis, solid and not deliquescent, terminating in simi- lar p) raniids, sometimes dihedral. In a moderate heat it melts, andjAvhen heated to ignition, deflagrates on the contact of any inflammable substance, with a bright flame, and a considerable hissing noise ; leaving, after detonation, its fixed alkaline salt, the acid being de- composed in the process. Oxygen and nitrogen gas are produced, and the result is the nitrumjixum of the older chemists; in fact, the kali. The origin of the acid of nitre has not been long known. When animal and vegetable substances,mixed with absorbent earths, have been exposed to the air till they arc thoroughly decayed, they are found to contain ;i small portion of nitre, or to give out a little nitre to water, on being supplied with the proper alkaline basis. On this foundation nitre is prepared in several parts of Europe; where they expose earth, wet with urine, or animal dung, with every kind of animal and vegetable substance, open to the air, but covered from rain : on the surface of these heaps a nitrous crust is found. The greatest quantities are brought to us from Persia and the East Indies, crude and of diff'erent colours; but the best is blackish, as it requires only solution and crystallization. When mixed with sea salt it is puri- fied as follows : 1-litre a solution of nitre, evaporate, and set it to crystallize in ii cool place. The crystals will remain sufficiently pure, for the sea salt i cmaius dissolved after the greatest part of the nitre hath crystallized. Nitre, according to Mr. Kirwan, when dried at the temperature of 70°, consists of forty-four parts of nitric acid, fifty-one of kali, four and a half of water. It is decomposed by the sulphuric acid, by barytes, by the muriat and acetat of barytes, and the vitriolated salts. See Chemia, vol. i. p. 414. Nitre is in part decomposed in the sal prunellae, more completely in the sal polycrest; but in each it acquires different portions of the vitriolic acid, from the sulphur with which it is deflagrated. In the former preparation one half, and in the latter an equal part, of sulphur is employed, which makes the sal polycrest wholly a vitriolated kali. The nitrous acid, formerly called Glauber's s/iirit of nitre, is made by adding to sixty ounces of nitre twen- ty-nine of a vitriolic acid. The mixtui'C is then dis- tilled. If two parts of nitre are added to one of oil of vitriol, the remaining alkaline basis of the nitre will be completely saturated with the acid, forming the vitriolated kali. If more nitre is used, part of it will remain blended with the vitriolated salt; if less, the re- siduum will not be neutral, but very acid. See Che- mia. The vitriolated nitre, ducis hohtatitie sal, sal de duo- bus; panacea du/ilicata; arcanum duplex; kali vitriola- :uni, IS usually made by decomposing the acid in the residuum, after the distillation of nitrous acid. It is the same with the sal polycrest. Thesimpleay«a/or//*oftheshopsismadebymixine nitre and green vitriol, not calcined, of each three pounds, with apound and a half of calcined green vitriol 1 his mixture is distilled with astrong fire, while any red vapours arise. The product is a spirit of nitre, con- taining so much more water than Glauber's spirit, as the vitriol employed docs more than an equivalent quantity of the oil of vitriol, and is liable to an admixture with the vitriolic acid, some of which generally passes over. For this the college order nitrous acid and distilled wa- ter, a pound of each, to be mixed together, and call it acidum nitrosum dilutum. Ph. Lond. 1788. In the aquafortis duplex, the green vitriol is calcined, and in equal quantity with the nitre, but is used only in the arts. The nitro muriatic acid, called agua regia, sometimes aqua stygia, and by Van Helmont chrysulea, is made by- adding gradually to an ounce of crude sal ammoniac in powder four ounces of the spirit of nitre. They should be mixed in a large cucurbit, and stand in a sand heat until the salt is entirely dissolved. Or, the salt may be powdered and gradually added to spirit of a middle strength, between single aqua fortis and strong spirit of nitre. The acid obtained from common nitre contains some of the marine and vitriolic acids : the first is discovered and separated by dropping in a little solution of silver ; the latter by a solution of chalk, in the pure nitrous acid; the silver absorbing the marine acid, and the chalk the vitriolic, forming, with those acids, indissoluble compounds. The solutions may be slowly dropped in, until no more milkiness appears. If the spirit is re- quired pure, it must be re-distilled. The cubic nitre is a combination of the nitrous acid with soda, and is prepared according to the following pioctbs. Dissolve chalk or lime in purified aqua fortis, .nnd add the solution, by degrees, to a solution of natron vitriolatum in water, while each fresh addition produces any milkiness. A white powder will be precipitated, which must bo separated by a filtre, and the fluid set to crystallize. The nitrum Jlammans of the elder chemists is the ni- trated ammonia of the moderns. It is very pungent, and dissolves in rectified spirit of wine. Solutions of calcareous earths in the nitrous acid are bitterish and pungent, crystallize with difficulty, and are deliquescent. The nitrous acid dissolves zinc, iron, reK'of«n th'''''-')'' ^^r^^'T, and silver, the mosl rodes thpf f ^-^f''' imperfectly, and it only cor- readilv wl?pnrr^'r^°>'' '^^^^^ ^^e latter most a ifgil^fluid ''Xt:st::x t ''-'-'''' ^-^-- The nitrous acid agrees in its tonic power with the other mmeral acids, but from its oxygen beinTmore loosely connected with the other componem nfrtrnr from the acid being more easily borneZthe stomach t has lately been preferred to the vitriolic and Cine' in cutaneous complaints, and other cases where riarl; proportion of oxygen appears to be wanting (see MofnT able medicine in .Sl^L^.tr^tLV'/nd^^ 'ln'aS°rnV'' '''' ^ h.mohkh/oJs^;'v.^' ^ in active inflammations of thp thr-^r,* 1 c m.re, held in .he „,ou,h, .mIo^I^ZT. Tu/t^Ted'