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ci the glafs were covered with a whitifh fcumwhich feemed moift, and a diminution of onecubic inch took place. Six more cubic inchesof fulphuretted hydrogen were added fuccefl'we-ly> a diminution took place after each,, fo thatat laft 11 inches, (namely 5 of fulphureous acidgas, and 6 of fulphuretted hydrogen) werereduced to 3, inches, part of which was folublein water,, and the remainder was azot. lhejar was coated with fulphur in the procefs, andwhen rinced out,, the water ufed for the purpofegave a white precipitate with the folutions ofbarytes, filver,. and lead, and lime-water, andcontained both carbonic and fulphuric acids. Thecolour of the precipitates of the above metallicfolutions proved that all the fulphur in the ful-phuretted- hydrogen had been feparated beforethe water was admitted to the refidual gas. Themutual aftions that take place between all thefefubftances mull be very complicated. On theone hand fulphur difl’olved in hydrogen is mixedwith a gafl'eous combination of fulphur notfaturated with oxygen, and the products are,much fulphur in fubftance, water and fulphuricacid, or fulphur Jaturated with oxygen, (thecarbonic acid and azot being put out of thequeftion, as being probably accidental impurities)and withal there is a great diminution in thebulk of the gaffes. Therefore we muff fuppofethat the hydrogen of the fulphuretted hydrogenunites with part of the oxygen of the fulphu-reous acid gas to produce water,, and therebydepofits in fubftance the fulphur with which itwas combined; and on the other hand thefulphureous acid being deprived of part of itsoxygen, depofits much of its fulphur in fub-ftance, whilft the remainder of its oxygencondenfes itfelf into another part of the fulphurand produces fulphuric acid. According to thisexplanation therefore, both the gaffes contributeto the formation of the fulphur, and certain itis that the quantity of fulphur is much too greatto arife folely from the fulphuretted hydrogen.

When 8 cubic inches of fulphuretted hydro-gen were mixed with 9 inches of nitrous gas, ayellowifti cloud appeared, together with a fuddenabforption, which gradually increafed, till after48 hours the whole was reduced to 6 cubicinches, and the top and fides of the jar werecovered with a white cake of fulphur. Therefidual air appeared to be nitrous oxyd. Thetheory of this decompofition is obvious, andmuch Ampler than the laft, the hydrogen of thefulphuretted hydrogen uniting with part of the®xygen of the nitrous gas, leaving the remainder

in the form of nitrous oxyd, and the fulphurbeing depofited unchanged.

Sulphuretted hydrogen and ammoniacal gasappear to combine totally if the ingredients arepure and in proper proportions. On adding 6cubic inches of the former to 7 of the latter gasa fmall white fcum appeared, but' in a fewfeconds the whole was reduced to y of an inch,and on throwing up water only -i of an inchremained. The water thus impregnated is afolution of hydro-fulphuret of ammonia, and,as appears, no decompofition takes place, forfcarcely any fulphur is depofited. This com-bination will be afterwards mentioned moreat large.

Sulphuric acid abforbs fulphuretted hydrogen.One meafure of the acid, of 1.863 fp. gr. wasfound by Mr. Kirwan to take up nearly 2meafures of the gas over mercury, and the acidwas whitened with a copious depofition offulphur.

Concentrated nitrous acid abforbs part of theair and feparates fulphur, but it is extremelydifficult to contrive an unexceptionable mode ofmaking the experiment, for the acid afts uponmercury, and if water is ufed, it dilutes theacid fo much that it no longer has the power ofdecomposing the gas and feparating the fulphur.

Alcohol readily abforbs about thrice its bulkof this gas. Water precipitates a part of thefulphur from it. Sulphuric ether alfo abforbsabout half its bulk of the gas.

It has been mentioned that the eafieft methodof procuring fulphuretted hydrogen, is by addingan acid to the alkaline, earthy, or metallicfulphurets.

In this cafe, as Gengembre has proved, part ofthe water of the acid is decompofed, its hydro-gen forms a gafeous combination with part ofthe fulphur prefent, and prckluces the fulphu-retted hydrogen, whilft its oxygen unites withanother portion of fulphur, and forms fulphuricacid, which is always found in the refidue inexatft proportion to the quantity of gas produced.

Sulphuretted hydrogen is alfo formed withoutany apparent decompofition of water, beingproduced in abundance by heating ftrongly amixture of fulphur with any fubftance thatyields hydrogen. Thus Mr. Kirwan obtainedit in large quantity by heating a mixture of twoparts of white fugar (previouily melted to ex’pelall the moifture) with one of fulphur. This gaswas very pure and contained neither carbonicnor any other acid. On the other hand amixture of fugar and fulphur moiftened with