g Some new Researches on Flame. 
three, for the carbonic oxide one. The coal gas contained only 
a very small proportion of olefiant gas; supposing it to be pure 
carburetted hydrogen, it would have consumed four of oxygen. 
Taking the elevations of temperature, and the quantities of oxy- 
gen consumed as the data, tne ratios of the heat produced by 
the combustion of the different gases, would be for hydrogen 
twenty-six, for olefiant gas 9-66, for sulphuretted hydrogen 6°66, 
for carburetted hydrogen six, for carbonic oxide six*. 
It will be useless to reason upon this ratio as exact, for char- 
coal was deposited both from the olefiant gas and coal gas during 
the experiment, and much sulphur was deposited from the sul- 
phuretted hydrogen; and there is great reason to believe, that 
the capacities of fluids for heat increase with their temperature. 
It confirms, however, the general conclusions, and proves that 
hydrogen starids at the head of the scale, and gaseous oxide of 
carbon at the bottom. It might at first view be imagined that, 
according to this scale, the flame of carbonic oxide ought to be 
extinguished by rarefaction, at the same degree as that of car- 
buretted hydrogen; but it must be remembered, as I have men- 
tioned in another place, that carbonic oxide is a much more 
combustible gas. Carbonic oxide inflames iu the atmosphere 
when brought into contact with an iron wire heated to dull red- 
ness, whereas carburetted hydrogen is not inflammable by a si- 
milar wire, unless it is heated to whiteness so as to burn with 
sparks. 
Il. On the Effects of Rarefaction by Heat on Combustion and 
Explosion. 
The results detailed in the preceding section are indirectly 
opposed to the opinion of M.de Grotthus, that rarefaction by heat 
destroys the combustibility of gaseous mixtures. Before I made 
any direct experiments on this subject, ] endeavoured to ascer- 
tain the degree of expansion which can be communicated to 
elastic fluids by the strongest heat that can be applied to glass 
vessels. For this purpose I introduced into a graduated curved 
glass tube some fusible metal. I heated the fusible metal and 
the portion of the tube containing the air included by it, under 
boiling water for some time. I then placed the apparatus in a 
charcoal fire, and very gradually raised the temperature till the 
fusible metal appeared luminous when viewed in the shade. At 
this time the air had expanded soas to occupy 2°25 parts in the 
tube, it being one at the temperature of boiling water. Another 
, experiment was made in a thicker glass tube, and the heat was 
E * These results may be compared with Mr.Dalton’s new System of 
Chemical Philosophy; they agree in showing that hydrogen produces more 
heat in combustioa than apy of its compounds, 
raised 
