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ffiulk of liquid. Collect thefe cryftals of nitratedbarytes, and wafh them with a little cold water,and they are now pure.

The nitrated barytes, either cryftallized ormerely evaporated to drynefs (according asmore or lefs nicety is required in the prepa-ration) is then to be heated in a porcelain retort,or earthen crucible fliglitly covered, to preventany of the fuel from falling in. It prefentlymelts, fwells up and gives out much azotic andoxygen gas, with a little nitrous vapour. Theheat is to be continued at a moderate rednefs,•till no more vapour or gas of any kind arifes,when the refidue will be found to be purebarytes, in the form of a grey fomewliat porousmafs, and if the heat has been too ftrong, partlyfufed with and adhering to the fides of the cru-cible. A conliderable time is required to deftroyall the nitric acid, when no more heat is ufedthan the crucible will allow of, but a platinacrucible is preferable, as the heat may be givenfreely without danger of vitrifying the barytes,which would render it itifoluble in water.

Barytes prepared in either of the abovemethods has the following properties : its tafteis like that of lime, but much more aerid andcauftic; and it changes the vegetable coloursas the alkalies do. When a little water is addedit abforbs it with great avidity, giving out muchheat, and becomes a {tiff pafte, which foonfolidifies and adheres ftrongly to glafs. f A fur-ther quantity of water changes it to a bulkywhite powder, which readily diffolves, efpeciallywhen heated, and on cooling it has the remark-able property of cryftalling in clulters of trans-parent needles. No other earth but barytes andftrontian can be thus artificially cryftallized.

Barytes is extremely foluble in water: whenboiling, water diffolves more than half its weight,the greater part of which cryftallizes on cooling,for cold water diffolves only a twenty-fifth ofits weight. Slowly cooled, the cryftals are finetranfparent prifms.

Barytes when heated on charcoal, by theblowpipe becomes hard and femivitrified in tex-ture, and is fcarcely again foluble in water. Itfeems to return by this procefs partly to theftate of carbonat, gaining carbonic acid fromthe flame of the lamp. When the blowpipe is.urged with oxygen gas, barytes readily melts.{nto a white enamel-like globule.

Barytic water (or a folution of barytes inwater) refembles limewater in abforbing carbonicacid from the atmofphexe, or from any gas-with which it may be in contact; only this

* .VaiKjuelin, An. Cli. ji.

takes place with much greater rapidity iti thebarytic folution, being much more concentratedthan the lime-water. Hence merely on pouringbarytic water flowly from one veffel to another,it becomes flightly turbid. The barytes as itbecomes carbonated falls to the bottom as awhite powder. Barytes is foluble in alcohol,but with difficulty unlefs affifted by heat. Theoxalic, citric, phofphoric and malic acids givecryftalline precipitates with faturated baryticwater, which are refoluble with a flight excelsof the fame acid. Moft of the metallic folution#are decompofed by barytic water, and the pre-cipitated oxyds of filver and lead are again diftfolved by an excefs of the barytes. s

Barytes, its carbonat, both native and artificial,and all its foluble falts are violently poilonous.

The combinations of barytes with the acidsare defcribed under the refpe&ive acids.

The affinity of barytes with the earths veryftrongly refembles that of the fixed alkalies infeveral important particulars. The powerfuladtion of barytes as a flux in a red heat hasbeen already mentioned, and the eafe with whichclay crucibles are corroded by it. The two fol-lowing experiments fhew this combination veryftrikingly. h Three parts of pure barytes weremixed with one of filex, and heated violently foran hour in a platina crucible. When taken out itwas a homogeneous, porous, friable mafs, fome-what green, tailing fweetiffi, and not heatingwhen flaked with water, as pure barytes does.It diffolved wholly in nitrous, muriatic andacetous acid, and gave a curdy precipitate withammonia, whereas the Ample folution of barytesis not difturbed by this alkali. Evaporated,this folution ftifFened to a jelly when nearlydry (a fure mark of the prefence of filex), andwhen folid the filiceous earth was left in itsproper character. Thus then barytes rendersfilex entirely foluble in acids, and potafh doesthe fame.

2. Nine parts of barytes were mixed withone of pure alumine newly precipitated fromits folvent and ftill wet, and the mixture was"boiled for a quarter of an hour with water.This yielded both a clear liquor and an earthyrefidue. The liquor was only flightly burningto the tafte, and though it abforbed carbonicacid from the air, and let fall a white baryticcarbonat, it would not cryftallize as pure barytesthough the quantity of water to the earth washut i'mall. Muriatic acid, only enough to fatu-rate the barytes, gave a flocculent precipitateof aluminy, which an excefs of the acid redif-

A Ibid. k Ibid. 29.