CAR ( 244 ) CAR
impoffible to afcertain any of its affinities in thedry way.
CARBONOUS OXYD, or Gafeons Oxyd
of Carbon.
The difcovery of the charattcriftic propertiesof this gas, and of thofe chemical characters bywhich it is diftinguifhcd from carburetted hydro-gen, hydrocarb.onate, or heavy inflammable air, isentirely due to Mr. Cruikfhank.
Till the refearches of this chemift, it hadalways been objedted by Dr. Prieftley againltLavoifier’s hypothefis of the conftitution of fixedair (and always with a force of argument whichonly the wilfully blind theorift could overlook),that when charcoal, however dry, was diftilledwith fcales of iron, or with the red oxyd of mer-cury, the product was not only carbonic acid,but a large quantity of a heavy inflammable air,which in l’ome refpects refembled the true car-buretted hydrogen obtained by diftilling moif-tened charcoal in a red heat, and was miftakenfor it.
Carburetted hydrogen confifts of hydrogenholding fome carbon in folution, and were itproduced by charcoal mixed with any metallicoxyd, the prefence of the hydrogen could onlybe accounted for according to the antiphlogifticfyftem, by fuppofing fome water to remainunited wi«h the charcoal and to be decompofedduring the diftillation. But an inflammablegas is produced in great abundance, whateverbe the heat to which the charcoal is previouflyexpofed, and therefore were it really compofedof hydrogen, the obje&ion to the whole hypo-thefis founded on this experiment would be un-anfwerable.
Dr. Prieftley in the above inftance fuppofedthe water to be a conftituent part of the ironfcales, and to be feparated from it by the phlo-gifton of the charcoal uniting with and revivingthe iron, but it is rendered more than probableby Mr. Cruikftiank’s difcovery that water is notin the leaft neceffary in the one or the other cafeto the production of that kind of inflammablegas produced by the above method, that this gasneceffarily contains no hydrogen whatever, buthas only a fingle combuftible bafe, namely, car-bon, and that with the fame two ingredients ascarbonic acid, it only differs from it in containingproportionally lefs oxygen, or in other wordsthat it is an oxyd of carbon. Therefore it bearsthe fame analogy to carbonic acid as the nitrousoxyd does to the nitric acid, the oxyd in eachcafe not containing fufficient oxygen to impartthe properties of an acid.
* Phil. Journ. vol. v. 4to. d An.Chim.
The experiments of Mr. Cruikfhank 1 havebeen repeated with much apparent accuracy byMeffrs. Deformes and Clement, b and the refultsof the two correfpond very clofely.
The gafeous oxyd of carbon may be procuredby fcveral methods, that is, either by the partialoxygenation of charcoal by diftillation with me-tallic oxyds ; or by the partial difoxygenation ofcarbonic acid by diftilling the earthy carbonatswith the filings of different metals; or by heat-ing carbonic acid with charcoal, whereby theproportional quantity of the carbonous bafe isencreafed ; or by the decompofition of carbonicacid by the eledtric fpark.
Oxygenation of Charcoal by Metallic Oxyds.
The original experiment of Dr. Prieftley isthe following: c Equal parts of the fcales of ironand charcoal (each having previoufly been madevery hot in feparate veffels) were put into aglazed earthen retort and ftrongly heated. In-ftead of a produft of •water , which Dr. Prieftleyexpended, a prodigious quantity of air came over,which on examination was found to confift ofonly one-tenth of fixed air, and the remainderwas an inflammable air of a very remarkable kind,being quite as heavy as common air. “ The reafon“ of this,” Dr. P. adds, “ was very apparent“ when it was decompofed by dephlogilticated“ air, for the greater part of it was fixed airThe above two important properties of this kindof inflammable air, namely, its weight, and itsalmoft total convertibility into carbonic acidwhen faturated with oxygen, are fully confirmedby fubfequent experiments.
Repeating this experiment of Dr. Prieftley,Mr. Cruiklhank mixed fome of the fcales, or im-perfect oxyd of iron feparated in forging, withpowdered charcoal (each being previoufly heatedfor an hour to rednefs before mixture) put theminto a coated glafs retort and heated gradually,receiving the gas in the pneumatic ciftem overwater. As foon as the retort was red, abundanceof gas came over, which being examined at dif-ferent periods was found in the beginning of theprocefs to be compofed of one part of carbonicacid and four of an inflammable gas (afterwardsdifcovered to be the carbonous oxyd, with afmall admixture of carburetted hydrogen:) afterwhich, to the end of the procefs the proportionof the carbonous oxyd encreafed to about fix-fevenths of the whole. Two ounces of thematerials yielded many gallons of the gas.
The fublimed oxyd of zinc was next fubfti-tuted to the iron fcales and diftilled with char-coal. Even before the retort became red, much