370 Experimentsvand Obfervations 
a ftrong elafs jar, inverted over mercury: when fired ‘they 
were reduced to 1 meafure, which was all abforbed by lime 
water, admitted for the purpofe, except a fmall ‘particle 
which was found from the nitrous teft to be pure air. From 
many’experiments Mr. Cruickfkank found that 12-meafures 
of oxygen gas, united with carbon, produce 'to of ‘carbonic 
‘acid gas. Hence it follows, that the quantity of oxygen gaz 
neceffary to the formiation of carbonic acid gas muft’in this 
cafe have been 1°1 meafures or a little better; the remain- 
ing *4 therefore were confumed in the produétion of water, 
aiid would be fufficient to faturate °8 of hydrogen, equal in 
weight to 048 of a gr. nearly.—Now 4 oz. meafure of ear- 
bonic acid gas weighs 864 of a gr. and this contains “24 of 
pure charcaal; hence the quantity of charcoal to hydrogen 
- $n this inflammable gas muft be as *24 to 048, or '5 to 1. 
But one meafure of pure hydrocarbonat, fuch as may be ob- 
tained fromthe decompofition of ‘camphor, by making its 
‘Vapour pafs through a red hot earthen tube, or from the 
‘diftilation of animal fubftances, opium, &c. requires 2 of 
‘pure air to faturate it, and the quantity of carbonic ‘acid 
‘amounts to 1°45, which makes the proportion of carbon’ to 
hydrogen as 12 or 13 to¥: hence thefe gafes differ! mate- 
‘tially, and ought not to be confounded. Indeed the differ- 
‘ence between them is manifeft from the manner in which 
‘they burn when mixed with common air, and brought into 
“contact with an ignited body: pure hydrocarbonat burns 
“flowly with a perfectly white flame, and ‘never detonates— 
on the: contrary, the compound inflammable’ gas, juft men- 
‘tioned, burns rapidly with a reddifh blue flame and more or 
lefs of a detonation. It was neceflary to mention’ this ¢ir- 
cumftance, as much’ confufion’ might be produced’ by ap- 
plying the fame name to fabftances’ confiderably different. 
{t is remarkable that ether, deeompofed’ by heat, affords 
pure hy drocarbonat, while alcohol yields the mixed {pecies. 
~ An ounce of gum tragacanth treated in the fame manner 
as 
‘, 
