M U R
M U R
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may be again brought to the fame cryftallizedmats by evaporation and cooling.
Muriat of lime has no fmell. The yellowifhcolour which it lias is probably owing to theimall quantity of iron which is contained inalmoft every calcareous earth, and alfo in com-mon muriatic acid. The tafle is acrid, bitter,and naufeous.
The folubility of this fait is indefinite in awarm temperature, for it readily melts in itswater of cryftallization when heated. Coldwater will diffolve twice its weight, 'and hencethe folution muft be extremely concentratedbefore the fait will feparate in a folid form bycooling. If a folution fo far concentrated as tocryftailize by cooling be poured hot into a bottleand immediately corked, it will remain fluidfor fome time when cold, if quite at reft, andthen when the cork is drawn and the bottlefhaken, the whole will folidify in a few fecondswith the evolution of fo much heat that thebottle cannot be held in the hand. This ex-periment however does not always fucceed, norwith fo much certainty as with Glauber’s fait.
Muriat of lime heated per fe firft liquefies andas it dries puffs up extremely and turns to awhite laline mats ftill deliauefceut. If the heatbe continued it parts with a portion of its acidbut not the whole. Beaume has the followinganalytical experiment on the fubjefl. Fourounces of muriat of lime heated for three hoursin a fire gradually raked to rednefs, gave anounce of good colourlefs muriatic acid, and themafs remaining in the retort was white, fpongy,and fiiline. Three ounces of cold water wereadded which immediately acquired a boilingheat, and on adding more water and filtering, aclear folution of muriat of lime was obtained,and a quantity of infoluble earth left behind.This liquor evaporated to drynefs and diftilledin a very ftrong heat till the retort was foftened,gave nothing more than a very flightly acidulouswater. Muriat of lime when heated in anopen crucible parts with more of its acid, butnever with the whole. The refidue from thediftillation of volatile alkali is phofphorefcentwhen heated. It is compofed of muriat oflime with excefs of lime, and probably alfoof fome undecompofed chalk. It forms Horn-berg’ s phcfphorus.
Muriat of lime is very foluble in alcohol.When rectified, alcohol diffolves its ownweight.
.Pelletier relates a curious.and unaccountablephenomenon. If carbonic acid is palled through■i- folution of muriat of lime the whole presently
changes into a fubftance fo folid as to require ftftrong ftroke of the hammer to break it.
The fulplume acid decompofes this fait, andowing to the fparing folubility of the fulphat cflime and the high lolubility ot the muriat, iffulphuric acid is poured into a concentratedfolution of the latter fait, the whole immediatelyturns to a white folid mafs of calcareous ful-phat.
The compofition of this fidt is thus given byKirwan : fifty parts of pure lime faturated withmuriatic acid, form too of the muriat whenheated to rednefs, and too parts of muriat inthis ftate therefore contain 50 of lime, 42 ofacid, and 8 of water.
This fait has fome not unimportant ufes inchemiftry. From its great tendency to deli-quefcence, it is valuable in the experimentson gafes to • abforb the moifture from them.For the fame reafon alcohol is brought to avery high degree of reftification when diftilledoff the dry muriat. The cryftallized muriatalfo affords the cheapeft and moft powerful fub-ftance as a freezing mixture, to produce themoft intenfe degrees of artificial cold, as men-tioned under the article Freezing.
This fait is never found native. It may beprepared by difl'olving either the natural or arti-ficial carbonat of barytes in muriatic acid, orfrom fulpliuret of barytes and muriatic acid,or from muriat of lime and fulphat of barytes,all of which methods are deferibed under thearticles Barytes and Carbonat of Barytes. Muriatof barytes cryftallizes readily from a hot con-centrated folution by cooling, or by flow evapo-ration. The cryftals are large, oi an opakewhite, and generally in oftogonal tables trun-cated at the angles. The tafte is acrid andaflringent. It is one of the heavieft falts known,and is readily diftinguifliable from moft otherfalts by its external properties.
This fait is not deliquefeent, nor in any wayalterable in the air. When heated it lofes itswater of cryftallization, but none of its acid.In a ftrong fire it melts, but is not in any otherway altered. About five parts of cold waterdiffolve one part of the cryftallized fait, andboiling water fomewhat more, but to cryftailizeit readily by cooling, it muft be confiderablyconcentrated by evaporation. It contains 64of barytes, 20 of acid, and 16 of water of cryf-tallization.
Sulphuric acid and every foluble fait contain-ing it decompofes muriat of barytes, and formsan inioluble iulphat of barytes, and this takes