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and the fulphuretted hydrogen to he but an ac-ceffary ingredient; whereas in the fulphurettedhydro-fulphurets the fulphuretted hydrogen ap-pears the principal folvent of the fulphur, andthe alkali to a£t as it were, as an intermede torender this union more permanent.

7. Simple Liquid Sulphurets. On the autho-rity of Proud whofe experiments have been al-ready detailed, we may admit the exiftence of afimple liquid folution of fulphur in alkali whenthe fulphuretted hydrogen has been withdrawnby adding red oxyd of mercury. This liquiddepolits fulphur copioufly on adding acids, butdoes not effervefce, and gives out no fulphu-retted hydrogen.

8. Fuming Ammoniacal Hydro-fulphurets andLiquid Sulphurets. The liquid combinations offulphur or fulphuretted hydrogen, or both toge-ther, with ammonia, have the property of emit-ting white- fumes when the alkali is in excefs,which therefore mult be confidered as anotherfpecies of this ciafs of fubftances.

Sulphur unites dire&ly with all the metalsexcept gold and zinc. Chemifls have diftin-guifhed the different combinations of fulphurwith the metal, fulphur with the metallic oxyd,and fulphuretted hydrogen with the metallicoxyd, with or without an excefs of fulphur.Of thefe combinations the fimple fulphuret, orunion of fulphur with the reguline metal is byfar the moft intimate, and it is even doubtful ifthere can be a proper fulphuretted oxyd in thedry ftate. For if fulphur is mixed with a me-tallic oxyd and heated in a clofe veffel to theperfedt fufion of the mixture, a quantity of ful-phurous acid is always firft given out, owingto a deoxydation of the oxyd by a portion ofthe fulphur, and the metal (nearly if not en-tirely in a reguline ftate) remains in permanentunion with the remainder of the fulphur. Thisimportant fa£t has been clearly illuftrated bythe experiments of Proud’ on the oxyds andfulphurets of antimony. If 100 parts of anti-mony be diftilled with as much fulphur, all theexcefs of the latter flies off, and there remainsat laft 135 parts of fulphuret, which continuespermanent at a heat more'than fuflicient to vo-latilize fulphur alone. If on the other hand aquantity of oxyd of antimony equivalent to 100parts of the metal, be diftilled with as muchfulphur, a large quantity of fulphurous acidflies off along with the excefs of fulphur, andthe relidue is as before 135 parts of fulphuret.The other metallic oxyds appear to a£I in a

fimilar way, whence we may infer it as a generalrule that in all the dry combinations of a metaland fulphur, after the utmoft effeeft of expofureto a heat capable of fubliming fulphur has beengiven, the metal is nearly if not entirely regu-line, provided there has been fulphur enoughadded to engagotall the oxygen which the metalmay have contained.

When metallic folutions are decompofed bythe liquid alkaline fulphurets, the metal com-bines with the fulphur, and a part, at leaft, ofthe fulphuretted hydrogen is deftroyed, its hy-drogen uniting with the oxyd of the folution tobring it to the metallic ftate, and its fulphurmixing with the other fulphur of the fulphuret.Hence moft of the precipitates formed in fuchcafes are Ample fulphurets, and not hydro-ful-phuretted oxyds. It is even doubtful if therecan be a hydro-fulphuretted oxyd, for the firftadlion of fulphuretted hydrogen is to reducethe oxyd to the metallic ftate, unlefs inftead ofa complcat reduction, it brings it to the ftateof loweft oxygenation. The production offulphuretted hydrogen by the affufion of anacid on the precipitate formed in fuch cafes isnot a fatisfa&ory proof of its being a hydro-fulpliuvet, as it is with the alkaline and earthyhydro-fulphurets, for with the metallic com-pounds, the fulphuretted hydrogen may be ge-nerated by the aftion of the acid, inftead ofbeing merely evolved. This is obvious from theufual way of producing this gas by muriatic acidand fulphuret of iron, which therefore throwsmuch difficulty in the way of the analyfis of thefemetallic compounds. It alfo appears from thisthat there cannot be a fimple metallic hydro-fulphuret, but that this compound whenever itis formed muft always exift with excefs of ful-phur, for there is no other method of pro-ducing a hydro-fulphuret than by adding liquidfulphuretted hydrogen, or an alkaline or earthyhydrofulphuret to a metallic folution, and asalready mentioned a part of the fulphure ttedhydrogen mu ft be decompofed, and an excefs offulphur produced before any combination cantake place. The whole of this fubjedt howeveris ftill involved in many difficulties, and re-quires further experiments.

SULPHURIC ACID, Vitriolic acid, Oilof Vitriol . Acide fulfurique, Fr. Schivefelsaure tGerm.

This acid, perhaps the moft important ofany for its extenfive ufe, is faid to have beenfound by BaldaiTari in a concrete ftate, lining a

Jourru de Phyf. ton;.