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excefs in the folufion, and is diffolved in the phur is expelled more eafily, and the acid andpieces into a well clofed dry bottle. The ful- potalh remain behind. In all thefe proceffesphuret thus prepared is a hard, brittle, Alining, no fulphuretted hydrogen is given out providedheavy mafs, fomewhat vitreous in its fracture, the fulphuret and other fubftances be quite freeand of a deep brown or liver colour, whence from moifture.

the antient name of liver of fulphur. As long Liquid fulphuret of potafh is made either byas it remains dry it is without l'mell. On lay- dilfolving any of the dry fulphurets in water,ing a minute portion on the tongue it tafles which is done with the utmoft eafe, or byexceffively^fharp, burning and bitter, along with diffolving fulphur directly in a folution ofthe peculiar naufeous flavour of fulphuretted caullic potalh with a boiling heat. It is then ahydrogen. When the folid fulphuret is expofed yellow fetid liquor, exceffively acrid and caufticto the air it firft turns green, which pafles to if concentrated, changing vegetable colours likegrey, it alfo abforbs moilture pretty rapidly, and the alkalies j and alfo, like thefe, corrodingthen begins to exhale the odour of fulphuretted animal and vegetable matter. It dilfolves manyhydrogen, but it does not adtually deliquefce metals with rapidity, bringing them to the ftateas melted potalh alone does. When moift, it of a fulphuret. When kept for a time even inftains the Ikin of a yellowilh brown which is clofe veifels it depofits fulphur.difficult to remove. The liquid fulphuret is well known for the

This fulphuret however is not entirely pure, facility with which it abftradts oxygen fromfor being made with a carbonated alkali it common air or any mixture of oxygen, andretains fome carbonic acid, though much of it hence its ufe in Eudiometry , as has been fullyefcapes during the fufion, and hence on the explained under that article,affufion of an acid, carbonic acid gas rifes in When the liquid fulphuret is made withmixture with the fulphuretted hydrogen. The perfectly cauftic alkali, it gives out no fulphu-pure dry fulphuret mult therefore be made with retted hydrogen by heat, at lealt not in a heatdry cauftic potalh, melted with about Its own of boiling water, but when made with carbo-weight of fulphur. The mixture in this cafe nated alkali a confiderable quantity of gas isenters into fulicn, and the union is compleat given out which however is chiefly carbonicbefore it reaches a red heat. acid. This fulphuret is alfo foluble with eafe in

When cauftic potalh and fulphur are rubbed alcohol,together in a mortar they unite rapidly, the When muriatic or any other acid is added tomixture grows hot, and loon is converted into folid fulphuret of potalh, there is a copiousa yellowilh green mafs which exhales a fetid difengagement of fulphuretted hydrogen) mixedfmell. In this cafe the moifture which the with carbonic acid, if a carbonated alkali hadalkali abforbs from the air affifts the combination. been employed) and a large quantity of fulphurA folid fulphuret of potalh may alfo be is precipitated. The liquid fulphuret alfo givesformed by mixing dry fulphat of potalh with out with an acid a large quantity of the gas orabout a fixth of its weight of charcoal, and gafles, and the mixture becomes immediatelymelting the mixture in a red heat for a confide- turbid and thick by the abundant precipitationrable time. In this cafe the fulphuric acid is of fulphur. The latter when walhed and drieddecompofed by the charcoal with much intu- is very pure fulphur of a white or cream colour,mefcence, and the fulphur refulting from the and is called Milk or Magijlery of fulphur , ordecompolition unites with the alkali, and the Precipitated fulphur.

whole forms a dark brown fulphuret. This The action of mercury and its oxyds on thehowever is much lefs pure than die fulphuret liquid fulphurets and hydrofulphurets lias beenmade by direct combination, for befides any urged with great ingenuity .by Proud,* in ex-undeeompofed fulphat which it may contain, it planation of the nature of thefe compounds,holds in folution a quantity of charcoal. Char- Running mercury agitated with the pure colour-coal therefore is foluble in a red heat in this lefs hydrofulphurets is not changed in any de-fulphuret. When the dry folid fulphuret is gree, fo that this metal cannot take fulphur fromurged with a violent and long continued heat, hydrogen when they are in perfedt faturationthe fulphur is again driven out, along with part and united with an alkaline or earthy bafe. Butof the carbonic acid if a carbonated potafh had when the hydrofulphuret has begun to becomebeen ufed, and alkali alone remains. If a dry yellow by ffiort expofure to air, that is to fay,fixed acid fuch as the phofphoric or boracic be •when by an oxydation of part of the hydrogenmixed with the fulphuret and heated, the ful- the fulphur which was united to it becomes in

Journ. de Phjf. tom. 59 p. 5167.