CAR
CAR
( 250 )
ingredient exifted in the ftate of pure carbon or held over the furface, flaflies of blue lambentcharcoal. Therefore, as the only products of flame may fometimes be perceived fpreading tocarburetted hydrogen when burnt with oxygen a confiderable diftance. All that is not fabulousare carbonic acid and water, chemifts generally concerning the ignis fatuus is probably derivedfatisfied themfelves with eftimating the quantity from this fource. This fpecies may be termedof carbon contained in the gas by taking about 28 for diftinction the carburetted hydrogen ofper cent of the weight of carbonic acid produced, marlhes. In the purelt form in which it can beand let down the entire remainder as hydrogen, collected it is ufually mixed with about 20 perFor example, if 10© cubic inches of any gas cent, of azot.
weighing 15 grains, were totally refolvable into This gas i6 alfo given out very abundantly bycarbonic acid and water by combuftion with oxy- almoft every vegetable matter when fubjected togen, and if by the combuftion 54. cubic inches of a fcorching heat fufficient to decompofe them,carbonic acid weighing 25 grains were produced, When heated in clofe veflels much more hydro-the quantity of carbon originally contained in the carbonat is obtained than when burnt in thegas would be reckoned to be 7 grains (being 28 open air, the product in the latter cafe contain-per cent, of the weight of the carbonic acid) ing more carbonic acid. It would be endlefs toand the difference between 7 and 15, or 8 grains, enumerate the vegetable fources of this gas, butwould be confidered as the weight of the hydro- fome of the moft convenient or ufual methodsgen ; or in other words the gas would be called of obtaining it pure may be mentioned,a carburetted hydrogen, confifting of hydrogen The deitrudtive diftillation of any of theholding carbon in folution, in the proportions acetous falts has often been ufed. For this, letof 8 (by weight^ of the former, to 7 of the latter, any quantity of dry acetite of potafh be put intoBut it is obvious that this mode of eftimating a retort and heated gradually. The fait foonmull be totally erroneous in the cafe (probably melts in its water of cryftallization, puffs up,very frequent) of a mixture of gafeous oxyd of and would boil over if the neck were not keptcarbon and hydrogen gas, and hence no ap- very hot as well as the bottom. The firft pro-proach to analyfis can be obtained without afeer- dudls are, the air of the veflels and water, thentaining both the water and the carbonic acid when the acetous acid begins to be fcorched, aproduced, and even then fome uncertainty will large ftream of gas begins and continues withoutoccur, as will be prefently mentioned. interruption till the whole is fully red-hot, and.
So that it is poflible, and by no means im- little elfe remains in the retort but the alkali, inprobable, that there may exift three fpecies of a carbonated ftate. Along with the gas muchgaffes, all of which have a claim to the title of oil arifes at different times, and condenfes inhydrocarbonat or carburttted hydrogen , namely, the cool receiver. The gas, according to Dr.1 ft, hydrogen limply holding carbon in folution, Higgins’s very careful analyfis, a after the firft;or what correfponds with the original idea of a portions have paffed over, confifts of nothing buthydrocarbonat: 2nd. hydrogen mixed with ga- hydrocarbonat mixed with a variable portion offeous oxyd of carbon: 3d. a mixture of the two carbonic acid, which laft may be feparated byformer fpecies, or hydrogen gas and gafeous lime-water. The hydrocarbonat itfelf variesoxyd of carbon, with an excefs of carbon held conliderably. The firft part is much heavierin folution by one or both of thefe gaffes. This than the laft (though ftill lighter than commonlaft fpecies therefore might alfo admit of fome air) and appears to hold in folution part of thevarieties, according to the folv.ent of the carbon, oil, for on Handing fome time over water itHaving noticed thefe difficulties, we proceed becomes lighter, and is found to require lefsto the nature and properties of hydrocarbonat, oxygen for faturation than before. The averageas obferved by different chemifts. fpecific gravity of the firft and laft gas mixed,
Carburetted hydrogen gas is obtained in a which may be taken as an average of the whole,great variety of ways, and with very confiderable is to that of common air as 2 to 3.differences in fpecific gravity and proportion of Carburetted hydrogen is obtained in greatingredients. It is found native on the furface purity by fending the vapour of inflammableof ftagnant waters, marfnes, wet ditches, &c. vegetable matter through an earthen or glai*through which, if examined clofely, large bubbles tube palling through a furnace and kept red-hot•will be feen to fife in hot weather, and may be in the middle. The vapour of camphor, ether,increafed at pleafure by ftirring the bottom with alcohol, and other inflammables treated in this3 ftick* In clofe ftill evenings if a candle is way is converted into this gas, but a very great