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(hank, with the difference of producing thecombuftion immediately by ignition with theeleftric fpark. A remarkable variety in therefults was, a copious depofition of charcoal infine powder after the explofion of the oxymuri-atic and the carburetted hydrogen gaffes, whenthe latter was not lefs than half the bulk of theformer. In this cafe there was not fufficientoxymuriatic gas for faturation, but when morewas ufed, no charcoal was depofited, but, asmight be expefted, a greater quantity of car-bonic acid was produced. This feparation ofcharcoal only took place with the hydrocarbo-nats from camphor, ether, or alcohol, and withthefe this property was loft, by being kept fometime over water.

Carburetted hydrogen is readily decompofedby fulphur, which unites with the hydrogen byftronger affinity, forming fulphuretted hydrogengas, whilft the carbon is precipitated as a blackfooty powder.

Dr. Auftin appears the firft chemift who re-marked this fadt. His experiment is the fol-lowing h . Some fulphur and carburetted hy-drogen were introduced into a glafs retort, pre-vioufiy filled with, and inverted over mercury.Heat was applied till the fulphur fublimed. Themelted fulphur foon became red, and as it fub-limed it became quite black, and the retort wascovered with a black cruft. One-third of theair was by this procefs converted into hepaticair. The remaining two-thirds was carburettedhydrogen not fenfibly altered. Sulphur andcharcoal alfo when heated together in a glafs re-tort, yield much hepatic (fulphuretted hydrogen)air.

The Dutch chemifts already mentioned alfofound, that when carburetted hydrogen waspaffed over fulphur kept red-hot in the middleof an earthen tube, the products were fulphu-retted hydrogen gas, and the remaining fulphurin the tube was blackened by the admixture ofcharcoal.

Carburetted hydrogen has never yet been ap-plied to any common ufe out of the laboratory,but that which is procured by the diftillation ofcoal, is obtained fo cheaply, and gives fo muchlight and heat when burnt in a proper apparatus,that it has been propofed to be employed forvarious purpofes of illumination, to which itfeems admirably adapted.

Oi.efiant Gas.

The difcovery of this very lingular fpecies ofearburetted hydrogen is due to fome affociatedchepaifts cf Amfterdam, (Van Deiman, Van* Phil. Traof. voj, 80, p. 66.

Trooftwyck, Bondt, and Lawrenburgh) in theirexamination of the different products of thediftillation of fulphuric acid and alcohol, in thepreparation of ether . k This gas appears in thecommon procefs when the diftillation is nearlyat an end, but where the only object is to ob-tain it and not the ether, the fame proportionsbetween the acid and alcohol fhould be ufed,as may be fuppofed to be left in the retortwhen the common diftillation of ether is nearlyat an end, that is, about four to one •, therefore,mix gradually four parts of concentrated ful-phuric acid with one of alcohol, and put themin fmall bottles ufed for procuring gaffes. Muchheat is given out on mixture, and the colourbecomes brown, which gradually darkens to aperfeff black when heat is applied. The gasin queftion begins to be given out at tlie mo-ment of mixture, and proceeds fo rapidly thatthe heat muft be difcontinued as foon as thomaterials are become quite black, or they wouldboil over out of the veffeL

The gas thus obtained Is mixed with a littlefulphureous acid which appears to be more orlefs in quantity according to the greater or lefsheat ufed. It is feparated by walking the gaswith water containing a little ammonia, afterwhich the olefiant gas remains pure.^ No car-bonic acid is ever found mixed with it, thoughthis might be expected from the nature of thematerials,

Pure olefiant gas thus prepared is nearly asheavy as common air, being lighter only in theproportion of 905 to 1000. Its fmell is veryfetid after the fulphureous acid and ethereousvapour are feparated by walhing. It burns witha denfe flame like that of any of the oils or re-fins. Water neither abforbs nor alters it in anydegree. None of the common re-agents, gaffes,acids, or alkalies, produce any notable effedtexcept the oxymuriatic acid, but the phenomenathat occur with this acid are very curious.

Equal parts of olefiant gas and oxymuriaticacid gas being mixed together, a diminution ofbulk takes place immediately, a vifible vapourfills the veffel, heat is given out very fenfible tothe hand, and at the fame time feveral drops ofa thick pearl-coloured oil appear at the furfaceof the water over which the mixture is made,and immediately finks to the bottom.

It is from this fingular produ&ion of denfe oilwith the oxymuriatic acid, that this fpecies ofcarburetted hydrogen has acquired the name ofolefiant. When the oxymuriatic and olefiantgafles are mixed in about the proportion of four

* Journ. de Phyf. tpm. 40.