CAR ( 257 ) CAR
to three, the whole is abforbed excepting acci-dental impurities, and is converted into oil andwater, perhaps with a fmall portion of carbonicacid.
The oil generated in the procefs is heavierthan water, whitifh, and femi-tranfparent. Bykeeping, it becomes yellow and limpid. Itsfmell is highly fragrant and penetrating; itstafte, fomewhat fweet. It is partially folublein water, imparting its peculiar fmell. Caufticpotalh has no effect on the oil, but only fe-parates the fmall portion of oxymuriatic acidadhering to it, and renders it more fragrant.
Olefiant gas appears from many experimentsto have no other conftituent parts than carbonand hydrogen, like the purer of the commonhydrocarbonats, but contains a much largerportion of thefe ingredients, at leaft of the car-bon.
It is decompofed by fulphur like the otherhydrocarbonats.
The combuftion of the olefiant gas offersfome very curious experiments. When an ar-gand lamp is fupplied with it inltead of oil, theflame exceeds every oil and other hydrocarbonatin beauty and brilliance. 1 When mixed withoxygen gas and detonated by the eledtric fpark,the explofion is much more violent than withthe common carburetted hydrogen. Mr. Henryfound that only .03 of a cubic inch with .17 ofoxygen fhattered a ftrong glafs tube; and aVolta’s eudiometer 1 of an inch thick, was burftwith lefs than a cubic inch of the mixed gaffes.It is to be obferved in all thefe experiments,that when only a fmall proportion of oxygen isufed, much lefs than is required for faturation,the eledtric fpark only kindles the mixture, butwithout any confiderable explofion.
Another Angular property of the olefiant gasis the copious depofition of charcoal when it ismixed with a fmall quantity of oxygen, or withthe oxymuriatic acid, and kindled. When themixture of the oxymuriatic and olefiant gaffesis made, two or three minutes elapfe before theoil is entirely precipitated, but if this mixture isimmediately fet fire to, no oil is produced, butinftead, fo copious a depofition of charcoaltakes place, that the whole veffel is obfcured,as if it had been covered with lamp-black. Nomore of the acid gas fliould be ufed than is ne-ceflary to produce the combuftion.
A fimilar depofition of carbon takes place whenolefiant gas is mixed with juft enough of oxygento begin the combuftion. The Dutch chemifts mfound that it required two parts of oxygen to
m Ann. Chim.
i|- of the olefiant gas, and when this was fetfire to by the eledtric fpark, the veffel was en-tirely blackened with the precipitated carbon.
It fnould feem in the above experiments thatthe carbon is feparated by the abftradtion of afmall portion of the hydrogen, and that thislatter alone undergoes combuftion with the oxy-gen when in fmall quantity, for on examiningthe refidue no carbonic acid was produced.What is very remarkable, the refidue, notwith-ftanding the depofition of charcoal, and thecombuftion of a portion of the original gas,actually expands to nearly double its formerbulk, fo that in making the experiment in aclofe bottle, when it is afterwards opened underwater, gas rulhes out from die veffel inftead ofwater flowing in, as might have been expedted.The refidue is now no longer olefiant, but bycombuftion and other properties, it appears tobe little elfe than a pure carburetted hydrogenof the common fpecies.
The great excefs of carbon condenfed in ole-fiant gas is alfo fhewn by the large quantity ofoxygen required to faturate it, and the quan-tity of carbonic acid produced. Each of thefe(as expreffed in the table) is much larger thanfor every other fpecies of carburetted hydro-gen.
Olefiant gas was procured by the Dutch che-mifts not only from alcohol and fulphuric acid,but by trarifmitting the vapour of alcohol or ofether through a red-hot earthen tube. Theolefiant gas, however, appears not to be quitefo pure, but to be mixed with common car-buretted hydrogen. A very unaccountable cir-cumftance, occurred in thefe experiments. Theearthen tube was a tobacco pipe, which yieldedolefiant gas very readily, but on fubftituting aglafs tube, the gas was no longer olefiant, butAmple carburetted hydrogen. This differencedid not depend on the porofity of the earthentube, for when this latter was enclofed in a glafstube the gas was as before, olefiant; and evenwhen the glafs tube was filled with alumine,or with filex, and the vapour fent through, thefame effect was produced, but when filled withlime, carbonat of lime, or magnefia, the gas wasAmple carburetted hydrogen.
The whole of this very interefting part ofchemiftry requires further examination, efpeci-ally with a view to the formation of the oxydof carbon, and by fuch enquiries we may hopeto gain fome knowledge of the great naturalprocefies that are going on in the animal andvegetable kingdoms,tom. 43. p. 1J7.
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