On the aëriform compounds of charcoal and hydrogen; with an account of some additional experiments on the gases from oil and from coal

In this paper, after adverting to the sources, properties, and composition of carburetted hydrogen obtained from stagnant water, and of olefiant gas procured from the decomposition of alcohol; and after examining the agency of chlorine upon these compounds; the author proceeds to examine the gas procured by the decomposition of oil and of coal at high temperatures. The former, or oil gas, is shown to vary considerably in composition and properties, according to the temperature at which it is procured; and though no temperature short of ignition is sufficient for the decomposition of oil into permanent combustible gases, yet the lower the heat the more combustible is the gas, and better suited to artificial illumination. In analysing these gases, Dr. Henry always found them mixtures of olefiant, carburetted hydrogen, hydrogen, and carbonic oxide gases. Dr. Henry separated the first by the action of chlorine, and from the detonation of the residue with oxygen, as compared with an artificial mixture of known composition, he ascertained the relative proportions of its components.