CAR

CAR

( 248 )

the weights of the gafeous oxyd and of the oxy-gen confurrted in the combuftion.

Therefore we may reckon on an average thattoo grains of the carbonous oxyd obtained fromthe decompofition of the earthy carbonats withmetallic fubltances in its pureft poffible Hate,unmixed with any hydrogen, to be compofed ofabout 59 of oxygen and 41 of carbon.

In this calculation it may be obferved, theinferences from Mr. Cruikffiank’s obfervationsare corrected, by affuming more accurate pro-portions for the compofition of carbonic acid,Mr. C. ellimating only 20 per cent, of carbonin the acid, which is certainly much too low,as Lavoifier’s proportions have been amply con-firmed by other chemifts.

The experiments of Deformes and Clementagree very clofely with the above, thefe che-mifts deducing the compofition of the gafeousoxyd to be in 100 grains, 58.4 of oxygen and41.6 of carbon.

All the above calculations fuppofe a perfectuniformity in the compofition of the gafeousoxyd, and the details of the various experimentswill fupport this opinion tolerably well, confider-ing the great variety in the quantities of theaccidental impurities of the gas, both of hydrogenand of carbonic acid, and of carburetted hydrogen,excepting in the Angle inllance of the carbo-nous oxyd produced by palling carbonic acidover red hot charcoal, where, as already men-tioned, the quantity of carbon in the inflammablegas appears to be very variable, and to be muchgreater than when prepared in any other method.It is by no means improbable therefore that thecarbonous oxyd may be fuperfaturated withcarbon, part of which may perhaps be againfeparated by the action of affinities too. weak toproduce an entire decompofition of the oxyd.

A true combuftion of the gafeous oxyd ofcarbon takes place when it is mixed with theoxymuriatic acid gas. If the latter be recentlyprepared and added to the. carbonous gas indue proportion the whole mixture is convertedinto Ample muriatic acid and carbonic acid, theoxygen having paffed from the oxymuriatic acidto the carbonous oxyd and completed its acidifi-cation. Two meafures of the carbonous oxydwere mixed with 2-|meafures f of the oxymuriaticgas in a bottle which the mixture completelyfilled, the ftopper was put in, and the neckplunged under mercury. After twenty-fourhours the ftopper was taken out under water,which rofe immediately and occupied two-

e Cniiklhank. L Delormes and Clement,

1 Mem. de 1 ’.

thirds of the bottle. This firft abforption waschiefly that of the muriatic acid. The refiduumwas then agitated with lime-water, and thewhole was abforbed except about i of a meafure,which was azot, and doubtlefs an accidentalimpurity.

The oxyd of carbon when heated in contactwith phoi'phorus difl'olves a portion, and thenburns with a pale yellow. The phofphorus isneither depofited nor acidified by long {landing,or by being kept twenty-four hours over water. 5

The effect of hydrogen upon.-the carbonousoxyd is very ftriking. When equal parts ofthefe gaffes are mixed together and paffedthrough a glafs tube made red-hot, h a completedecompofition takes place, the gafeous oxyd de-pofits its charcoal on the lurface of the tube,which, being nearly melting, caufes it to adhereand to form a very brilliant uniform blackenamel, whilft the oxygen of the gafeous oxydby union with the hydrogen forms water, whichis condenfed at the further extremity of the tube.Some of the hydrogen paffes through apparentlyunaltered.

The decompofition of carbonic acid gas byelectricity, when in cootaCt with mercury, orfome other metallic body, and alfo by hydrogen,well illuftrates the nature of the carbonous oxyd.Dr. Prieftley was the firft who found a change totake place in carbonic acid gas by taking theele£tric fpark in it repeatedly for a confiderabletime.' Out of many experiments the followingmay be feleCted: in a fmall tube containingabout T V of an ounce in meafure filled withfixed air and {landing over mercury, the eleftricfpark was taken for an hour after which thewhole tube was clouded chiefly with a blackmatter, but at the bottom with a yellow fub-ftance like fulphur. Each of thefe fubftanceswas found to be part of the mercury by whichthe gas was confined and changed in the procefs.The air itfelf was a little enlarged, but the greatalteration produced in it was that inftead of beingall abforbed by water, as pure fixed air is, abouta fifth part remained infoluble in this fluid.

This curious experiment was repeated byMonge k with great attention, and with fimilarrefults with others of importance. II e foundthat when the eleCtric fpark is taken in fixed air,the volume of the gas fenfibly increafes, and thatthis enlargement goes on for a confiderable timethough the eledrization is fufpended: that itceafes after a certain time, and then the iron con-ductors (if this metal is ufed), are fo completely

■ Ibid. k Experiments on air, vol. i. p. 11 j.tcad. for 1786.