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remaining fulphuretted hydrogen, the mercuryextra£ls from the folution this excefs of fuiphur,(immediately, from the hydro-fulphuret of am-monia, and in a fhort time, from the otherhydrofulphurets) and the liquid returns tothe ftate of Ample hydro-fulphuret. A portionof the fulphuretted mercury remains dif-folved, whilft the folution is concentrated, buton diluting with water or alcohol it becomesturbid, and black fuiphuret of mercury is pre-cipitated, and the liquor is again reftored to theftate of Ample hydrofulphuret of the alkali em-ployed. If however the excefs of fuiphur is fogreat as to bring the mercury at once to the ftateof red fuiphuret none of it is diffolved, thoughthe fame change takes place in the liquor. Mer-cury therefore in the metallicJlate analyzes allthefe compounds of fuiphur, fulphuretted hy-drogen and alkali, by extraditing all the fuiphurexcept that portion which is faturated withhydrogen, and in the ftate of fulphuretted hy-drogen ; and hence it almoft entirely extractsthe fuiphur from thofe liquid fulphurets whichfcarcely effervefee with acids, and contain but aminute portion of fulphuretted hydrogen, andreduces them almoft to the ftate of fimple alka-line folutions.

But on the other hand a precifely oppofiteeffect takes place when the red oxyd of mercuryis ufed, for when this is agitated with a hydro-fulphuretted alkali, its firft adtion is to decom-pofe all the fulphuretted hydrogen which itcontains, which is attended with a fenfible evo-lution of heat; and if no more oxyd be ufedthan is neceflary to engage the hydrogen, theremaining liquor becomes yellow, but remainsclear after the fubfidence of the oxyd, and is afimple liquid fuiphuret, from which muriaticacid precipitates fuiphur, but without the evo-lution of a particle of fulphuretted hydrogen.If an additional quantity of red oxyd be added,the fuiphur is precipitated in combination withthe metal, and the fupernatant liquor is thenlittle elfe than a folution of potafh, holding alittle oxyd of mercury, and fometimes fuJphiteof potafh. A fimilar change takes place withthe common liquid fuiphuret of potafh, which,as already mentioned, contifts of fuiphur, pot-afh, and hydrofulphuret of potalh. The firftportion of oxyd engages the hydrogen of the hy-drofulphuret, and detaches the fuiphur belong-ing to it, which difTolves in the fuiphuret thatremains in folution, and by deftroying the hy-drogen, takes from the folution of the propertyof effervefeing with an acid. The oxyd alfo

lofes oxygen, which unites with the hydrogen,and the metal abforbs a portion of fuiphur andbecomes black fuiphuret, part of which remainsin folution. This firft change takes place with-out any effervefcence, and with difengagementof fenfible heat. But on adding a frefh portionof oxyd the heat is renewed, an effervefcenceoccurs owing to the efcape of part of the oxygenof the oxyd, the mercury becomes faturatedwith fuiphur and precipitates, and the remainderof the oxygen acidifies the fuiphur, and fulphitcof potalh is found in folution. '

The principal point eftablifhed by this ex-cellent chemift in thefe experiments, is thepoffibility of fubtrafting all the fulphurettedhydrogen from a liquid fuiphuret (at leaft tothat degree as to render it non-effervefeent withan acidj whilft the alkali and fuiphur alone re-main in folution ; and hence as the poffibilityof a fimple liquid fulphuretted alkali is eftab-liflied, it may fairly be inferred that fulphurettedhydrogen is not the principal intermede by whichfulplmr and potafh are held in liquid combina-tion in the common folutions of the fulphurets.

Sulphuret op Soda. This combination may bemade either dry or liquid, by all the methodsin which the fuiphuret of potafh is produced, andit has the fame general chemical propertieswhich have been deferibed as belonging to thefuiphuret of potalh.

Sulphuret of Lime. Lime being infufible perfe, the combination between lime and fuiphurcan fcarcely, if at all, be made in the dry way;but a liquid fuiphuret of lime is readily formedby boiling together fuiphur, lime, and water.The proportions are of not much confequence ;the following anfwer very well: put into aglafs mattrafs three ounces of well-burnt lime,one ounce of fuiphur, and about a quart ofdistilled water. The fuiphur fhould firft berubbed with a little of the water, that it maymix uniformly, and the lime fhould he brokendown. Bring the liquor to a boiling heat, andcontinue it for half an hour or an hour, (bakingit frequently during the time. The liquor foonbecomes clear by fubfidence as foon as removedfrom the fire, and a fine yellow ftrong folutionof fuiphuret of lime may be poured off clearfrom the fettlings, which fhould be kept in awell clofed bottle.

Though fuiphur is abfolutely infoluble inwater, and lime very fparingly foluble, thefuiphuret is confiderably fa, and when muchconcentrated when hot, part of it feparates bycooling into cryftals not eafily refoluble in the2 z 2