CAR
CAR
( 249 )
oxidated as to let fall fcales of oxyd from theirfurface, evidently {hewing a connexion betweenthe change of the gas and that of the metal. Heslfo found that after electrization that part ofthe gas which was not abforbed by caultic alka-lies (and confequently was not carbonic acid)was highly inflammable, and when mixed withoxygen it exploded by the electric fpark, as purehydrogen does. This made him confider thevefiduary gas to be hydrogen, nor could the ex-periment be explained otherwife before the dif-covery of the gafeous oxyd of carbon, which byfubfequent experiments this is found to be.
The elegant experiments of Theodore deSauffure have thrown further light upon thisfubjedt. 1 Electric fparks were taken for 18hours iu a glafs tube containing 13 cubic inchesof carbonic acid gas, pure and well dried, andconfined by mercury. After electrization, muchof the black oxyd of mercury defcribed byPrieftley was found, but the conductors, beingcopper, were not fenfibly oxidated. A veryflight dilatation amounting to no more than T Vof a cubic inch was perceived. On throwingup caultic alkali only one cubic inch was ab-forbed, which was therefore carbonic acid. Therefidue was not hydrogen, but very pure gafeousoxyd of carbon; for when 100 parts of it wereburnt with about one-third of oxygen gas no waterwas perceived, but the product was merely 77parts of carbonic acid. No chemift has yetfucceeded however in entirely converting car-bonic acid into carbonous oxyd, by electrization,but the quantity is obvioufly encreafed in pro-portion to the continuance of the eledtricpafiage.
Carbonic acid gas was alfo found by the fameingenious chemift to be decompofed by hydro-gen with the aid of the electric fpark. In along glafs tube, 34 parts (in bulk) of pure car-bonic acid mixed with as much hydrogen wereelectrified for 12 hours. A condenfation tookplace, confiderable at firlt, but towards the end,very flight. A number of fine drops of waterwere depofited on the upper part of the tube, andwhen the procefs was flopped, the bulk of thegafeous mixture was reduced from 7-k to 4^-parts, 1 of which was undecompofed carbonicacid, and the remaining proved to be thegaleous oxyd of carbon, being inflammable, un-abforbed by water or alkali, and when burnedwith a third of oxygen gas, giving carbonic acidin the proportion of 70 meafureS' to 100 of theinflammable gas. It alfo contained a fmall ad-mixture of hydrogen. When the procefs was
‘Jour, de Phyf. tom. liv.
finilhed in a day the metallic conductors werenot oxidated, nor the mercury altered.
In the above experiment the hydrogen appearsto unite with part of the oxygen of the carbonicacid to form the water that-is condenfed, whilftthe carbonic acid by lofing oxygen pafles to theftate of carbonous oxyd.
It appears from an experiment of Deformesand Clement ” 1 that hydrogen which has been{hewn to be fo powerful an agent in decom-pofing both carbonic acid and carbonous oxyd,fometimes effects a complete difoxygenation ofcarbonic acid without fenfibly palling into theintermediate ftate of carbonous oxyd. Hydro-gen gas pafled through a tube, containing thenative carbonat of barytes heated red hot, isfound to render the barytes cauftic or pure, andfometimes to feparate the carbonic acid as'fuch,but at other times to bring over a quantity of ablack carbonaceous powder, which is condenfedin the water of the recipient, and which thefechemifts fuppofe to he the carbon of the decom-pofed carbonic acid.
A decempofition of carbonic acid by hydrogen,fimilar to that by electricity related by Sauffure,alfo takes place when the mixed gafles are pafledthrough a red-hot porcelain tube, and thegafeous oxyd is produced.
CARBURETTED HYDROGEN GAS.
Hydrocarbonate , or Heavy Inflammable Air. GazHydrogene Carbone , Fr. Kehletiflqjfhahiges Waf-feiflflgas, Germ.
The only definition that can apply to car-buretted hydrogen as generally defcribed, is, aninflammable gas confiderably lighter than com-mon air, not rendering lime-water turbid when{haken with it, and when burned with oxygentotally refolvable into carbonic acid and water.
It {hould be obferved that many of the moilimportant experiments on this gas were madeprevious to the difcovery of the true nature ofthe carbonous oxyd, which difcovery, whilft itaffifts in the explanation of feveral difficult phe-nomena in chemiftry, throws fome uncertaintyon the refults of former enquiries into the pro-perties of carburetted hydrogen, and renders afurther examination highly neceflary.
Before it was fufpected that carbon couldexift in any other ftate of oxygenation than ascarbonic acid, it might be inferred with tolerable(though not abfolute) certainty that when anygas had been purified from carbonic _acid byagitation with alkali ’ or lime-water, if it fur-niflied a frefh portion of carbonic acid aftercombuftion with oxygen, the carbonous in-** An. Chim. tom. xliiit p. *88.
2 I
TO L. 1.