CAR
CAR
( 254 )
oxygen 13O5 inftead of 137: from camphor,104, inftead of 116: from ether, 100, infteadof 108: and from alcohol, 69, inftead of 75,■which numbers correfpond tolerably well.
Another circumftance to be particularly re-marked is the very variable quantity of hydro-gen which is inferred from the refidues, aquantity which fometimes far exceeds and fome-times as far falls (hort of 100 cubic inches, thequantity employed, and which obvioufly (hewsfome great error in the inferences drawn fromthe experiments. For, taking the gas from coal asan example, fuppofing it to anfwer to the gene-ral idea of a hydrocarbonat, that is, to confiftlimply of hydrogen gas holding carbon infolution, the oxygen required to faturate 10ameafures is fuppofed to be divided into twoportions, one of them amounting to 100 mea-fures, going to form the carbonic acid, and theother amounting to 70 meafures, entering intothe compofition of the water produced.
But 70 meafures of oxygen require for thispurpofe 140 meafures of hydrogen of the ordi-nary denfity, whereas the whole amount of theinflammable gas is only 100 meafures, andtherefore the hydrogen of which it is compofedmuft be denfer than common hydrogen atleaft in the proportion of 14 to 10, even ne-glecting the fpace occupied by the 13 grains ofcharcoal which the gas is alfo proved to contain.But if any of the carbon exifts in the 100 mea-fures of the inflammable gas in the ftate of thegafeous oxyd it muft of courfe occupy morefpace than when as mere charcoal, and of courfelefs fpace can be allowed to the hydrogen, and itmuft be ftill more condenfed.
This condenfation of hydrogen in the diftilledproducts of vegetable inflammables is in itfelfhighly probable, and indeed is inferred from themuch higher fpecific gravity of carburetted
hydrogen than pure hydrogen ; but if this con-denfation be allowed m fome hydrocarbonats,an oppoffte Jlate cannot be fuppofed in otherhydrocarbonats, where the fpecific gravity isequally great. Yet this inference muft followin thofe cafes where the quantity of hydrogenis inferred as above from the refidue of oxygen,when it is lefs than the original bulk of the in-flammable gas. Thus in the gas from fugarthe eftimated refidue of oxygen is only 20 cubicinches, and therefore the hydrogen which itinfers is only 40 inches, whereas the quantityof inflammable gas actually ufed was the inches,and therefore were this mode of computa-tion juft, this carburetted hydrogen ought to berarer than common hydrogen, in the proportionof 4 to 10, a fuppofition obvioufly withoutfoundation.
This part of the difficulty may be obviatedby the very probable fuppofition that a part ofthe gas confifts of the carbonous oxyd, whichbeing mixed with carburetted hydrogen willgive the fame general appearances on com-buftion as fimple carburetted hydrogen, andbeing much heavier, will account for part ofthe great fpecific gravity of this kind of inflam-mable air. Where the calculation is merelyhypothetical, it may eafily be fo arranged as tofupply by arbitrary quantities of charcoal andcarbonous oxyd all the deficiencies of the efti-mated hydrogen. Of this the following willferve as an example.
Suppofe as in the above inftance 100 cubicinches of the gas from fugar require 100 inchesof oxygen for faturation, and produce 80 cubicinches of carbonic acid (which are all the fallsadvanced) then the original 100 cubic inchesmight be thus diftributed, without requiringeither expanfion or condenfation of the hy-drogen.
Inflammable Airfrom Sugar
cub.inch.
Carbon* Oxyd 30Hydrogen 70
grains
Charcoal 6.9
Oxygen
with
cub. inch.
12 .
3553
produce
100
xoo
S 3 -
80.6
Water
This mixture is of courfe quite arbitrary, and mable gas yielding carbonic acid and water byit is obvious that if a condenfation of the hy- combuftion can be properly analyzed till th edrogen were fuppofed, the proportions might be quantities both of the acid produced, and of th*varied; and it is likewife clear that no inflam- water are feparately eftimated.