NIT
NIT
( 1 66 )
The compact dry nitrat of ammonia, heated■without addition in a fmall glafs retort, withthe bulb of a thermometer inclofed, was foundto undergo little or no change at a heat below260°. From 275* to 300° it flowly fublimeswithout decompofition or without becomingfluid. At 320 it becomes fluid, flowly fublimes,but alfo now begins to be decompofed and togive out gaffeous nitrous oxyd. From this theheat may be lafely raifed to about 440*, atwhich it is totally refolved into the gas, and isdilhpated without leaving any refidue. Theprifmatic and fibrous varieties of this fait asthey contain more water, of cryfballization, be-come fluid below 300°, and if not heated above43o°, they part with this water before they aredecompofed into nitrons oxyd. The further pro-.perties of this gas will be defcribed under thatarticle.
This fait is prepared artificially by diffolvingin dilute nitric acid the native or artificial carbo-nat of barytes, the methods of procuring whichare defcribed under that article.
On evaporating the folution and cooling, thenitrat of barytes feparates generally in regularodtohedrons. This fait is of an opake-white,hard, and not deli.quefcent. It is one of theleaf; foluble of all the nitrats, requiring twelvetimes its weight of water at 60 °, and about fourparts of boiling water. Hence nitric acid pouredinto a concentrated folution of muriat of bary-tes, will caufe an immediate white precipitate,which however is refoluble in more water, andis nitrat of barytes.
This nitrat is compleatly decompofed by heat,•the acid is driven off) and the barytes remainspure and cauftic, as already mentioned underthe article Barytes .
The production of this fait in calcareousbuildings, &c. that have been ufed by animals,and its intimate connexion with the manufactureof nitre, has been fully defcribed under thearticle Nitrat of Potafi.
Nitrat of lime may be made artificially ingreat purity by faturating nitric acid with whitemarble or calcareous fpar. 1 his folution whenevaporated to a very thick fyrupy confiftence,cryltallizes in a cool air into long prifms re-fembling bundles of needles diverging from acommon centre. If further evaporated, thefolution when cold concretes into a fibrous andihapelefs mafs.
This fait is bitter and pungent. It diffolvesin its own weight of boiling water, and twice its
weight of cold water. It is very deliquefcent.When heated per fe, all the water and acid aredriven off, and only pure lime remains, but ifthe heat be too llrong it vitrifies with the cru-cible employed, if of earth. Lime has beenfaid to be cryftallizable in this way, but the ex-periment has not fucceeded with many accuratechemifts.
This fait is readily prepared by faturatingdilute nitric acid with the native or artificialcarbonat of ftrontian (either of which it readilydiffolves) and evaporating the folution, whichforms odtohedral cryftals much refembling thenitrat of barytes in appearance, but much morefoluble, requiring only five parts of cold waterfor their folution-
This fait is alfo compleatly decompofable byheat, and the ftrontian is left pure, fo that itmay readily be made to cryftallize, as 1 will befurther mentioned under the article Strontian.
Nitrat of ftrontian like many other falts withthis balls give a red flame to burning ■alcohol.
This fait when cryftallized affumes .the formof rhomboidal prifms with obliquely truncatedfummits or of needles for the molt part ad-hering to each other. Its fp. gr. is = 1.73.Its tafte is pungent and bitter like that of ni-trated lime. It is faid by Fourcroy to occurnative and in nitre beds, and to be containedin the mother water of nitre, which is by nomeans improbable. When wanted however forchemical examination it is prepared by fatu-rating nitrous acid with magnefia either pureor carbonated, and then evaporating the folutionto an oily confiftence and fubfequent cryftal-lization.
Nitrat of magnefia when expofed to the airattradls moifture, and at length, though flowly,is refolved into a fluid. If heated in a crucibleit firft melts in its water of cryftallization, andafter this has evaporated it becomes dry. Onincreafing the temperature it gives out a littleoxygen gas, which is prefently fucceeded bynitrous vapour and nitrous acid, nothing re-maining behind except the earth in a ftate ofpurity.
This fait is foluble in its own weight of waterat 50° Fabr. and in a confiderably fmaller pro-portion of boiling water ; hence it depofits cryf-tals by cooling. It is alfo foluble in nine timesits weight of alcohol.
When heated with combuftibld fubftances itgives out a few fparks, but cannot, properlyfpeaking, be faid to detonate.