Description of an Apparatus for the Analysis of the Compound Inflam-
mahle Gases by slow Combustion ; with Experiments on the Gas from
Coal, eaplaining its Application. By William Henry, M.D. Vice-
Pres. of the Lit. and Phil. Society, and Physician to the Infirmary,
at Manchester. Communicated by Humphry Davy, Esq. Sec. R.S.
Read June '23, 1808. [Phi]. Trans. 1808, p. 282.]
The object of this memoir is to remove some obstacles which pre- sent themselves to a successful inquiry into the nature of compound inflammable gases. When a vegetable substance is submitted to dis- tillation, at a temperature not below that of ignition, the equilibrium of aflinities is destroyed, and the elements composing it are united in a new manner. The carbon, uniting with oxygen, either composes carbonic acid gas, or stopping short of that degree of oxygenation, is converted into carbonic oxide. The hydrogen, combining with a. portion of charcoal, forms either carburetted hydrogen gas, or super- carburetted hydrogen, better known by the name of olefiant gas. Towards the close of the process, simple hydrogen gas is also min- gled with the products.
The method hitherto pursued for the analysis of inflammable gases, has consisted in mixing them with a known proportion of oxygen, burning the mixture by the electric spark, noting the first contraction and subsequent diminution, by lime-water, for the quantities of water and of carbonic acid formed, and thence inferring the proportion of hydrogen and of carbon in the gas examined, without making due allowance for the possible admixture of carbonic oxide, either before or after the combustion.
The author ascertains the presence of this gas by its great specific gravity, and by the very small proportion of oxygen with which it unites; but in the distillation of coal there is also often present a quantity of sulphuretted hydrogen, and an inflammable gas, which may possibly be a gas sui generis, but is more probably a mixture of carburetted hydrogen and carbonic oxide.
In Dr. Henry’s apparatus, which is not readily explained without reference to a drawing, the gas to be examined is passed through a small tube into a receiver containing oxygen gas, and is there burned by a continued flame. The quantity of gas introduced, and quantity of contraction, are noted. The quantity of carbonic acid formed is found by liquid potash. The remaining oxygen is determined by sulphnret of lime. As it sometimes happens that part of the gas escapes combustion, precautions are given for avoiding that source of error, and the means of detecting it described.
Instances are given of computation, from combustion, of hydrogen gas, of olefiant gas, as the most simple, and of gas from cannel coal, in which it is a problem of some difiiculty to determine the prepartions of all the gases that occur; and these are carbonic acid, sulphuretted hydrogen, olefiant gas, carburetted hydrogen, and carbonic oxide.
The sum of the two first is dctermined by liquid potash, after
