74 On the aériform Compounds 
hy drogen gases is fired with oxygen, and an equal volume of the 
same mixture is first deprived of olefiant gas by the action of 
chlorine, and then fired with oxygen, it must necessarily happen 
that the excess of oxygen spent in the first combustion, above 
that consumed in the second, will be three times the volume of 
the olefiant gas, and that the excess of carbonic acid formed in 
the first experiment above that generated in the second, will be 
double the volume of the olefiant gas. A remarkable anomaly, 
however, was during the last summer observed by Mr. Dalton 
in the results of the combustion of a quantity of gas, which he 
had himself prepared from oil. One volume was found to con- 
sume three volumes of oxygen, and to yield little short of two 
volumes of carbonic acid, in those respects agreeing nearly with 
olefiant gas ; but when mingled with more than the requisite pro- 
portion of chlorine, it was not, as olefiant gas would have been, 
entirely condensed, but suffered a diminution of only four-tenths 
of its bulk, the remaining six-tenths, after being freed from the 
redundant ‘chlorine, agreeing in its properties with carburetted 
hydrogen. For example, 10 volumes of this gas (containing four 
of gas condensable by chlorine and six of carburetted hydrogen) 
consumed 30 volumes of oxygen, and gave 18 of carbonic acid. 
But of the oxygen, 12 volumes are due to the six of carburetted 
hydrogen, leaving 18 volumes for the combustion of the four 
volumes of gas condensable by chlorine, which is in the propor- 
tion of 44 tol. Of the 18 volumes of carbonic acid, also, six 
may be traced to the combustion of the carburetted hydrogen, 
leaving 12 volumes as the product of four of the condensable gas, 
or in the proportion of 3 to 1. The portion of gas condensed 
by the action of chlorine presents, therefore, decided differences 
from olefiant gas, in requiring not three only, but 43 volumes of 
oxygen for combustion, and in affording 3 instead of 2 volumes 
of carbonic acid. Nearly the same relation of the oxygen con- 
sumed, and carbonic acid produced, to that part of the gases 
from coal and oil which is condensable by chlorine, existed also 
not only in other experiments of Mr. Dalton, but in all those 
which I have myself made. ‘The proportions I have found to 
vary in different cases from 41 to 5 volumes of oxygen, and from 
24 to 3 volumes of carbonic acid for each volume of the con- 
densable gas. 
On comparing also the specific gravity of the gases from coal 
and oil, as ascertained by experiment, with that which ought to 
result from mixtures of the residue left by chlorine, with such a 
proportion of olefiant gas as is deducible from analysis, I have in- 
variably found, that the real specific gravity has considerably ex- 
ceeded the estimated. For instance, the London oil gas was 
composed of 35 volumes of a gas condensable by chlorine, and 
\ +.) 
