WATER-GAS, a term first applied to hydrogen on account of its being the gas which was liberated when steam was brought into contact with red-hot iron; the oxygen of the steam uniting with the iron, forming oxide of iron, while the hydrogen was evolved. Subsequently it was discovered that, when carbon was employed in place of iron, there was not only hydrogen liberated, but oxide of carbon, which is also a gas; it was then found that, if this mixture of hydrogen and oxide of carbon was enriched by the addi tion of naphtha, etc., it would make an illuminating gas; but so far as known, there was no practical application made of this fact till 1830, when Michael Donovan patented a process for the manufacture of an illuminating gas composed of hydrogen and oxide of carbon, enriched to give it illuminating power, which was called water-gas, and was essentially the same as is now manufactured under that name. A Belgian by the name of Jobard obtained a patent for water-gas in 1832; and later, George Lowe, an English engineer, also obtained a patent. M. Selligne, of Paris, employed three iron retorts for making water-gas, two of which contained charcoal, while the third was two-thirds filled with red-hot iron chains, upon which a slow stream of shale oil was allowed to Dow. Steam was passed into the first retort, where it was decomposed; from thence into the second, where the red-hot charcoal converted any CO, (carbonic acid) into CO (carbonic oxide). The gases then passed into the third retort containing the red-hot chains upon which the "shale oil" was flowing and being vaporized, thereby imparting to the gases illuminating properties. Later, Mr. Kirkham, an English engineer, took hold of the
process, aud, in 1852, it was patented in England by Messrs. John and Thomas Kirk ham. An attempt was then made to introduce it into England, but without much suc cess. It was then taken to Paris and there created considerable excitement, and was about to be extensively introduced, when, by some misunderstanding in regard to its poisonous properties, it was abandoned. In 1871 there was introduced into this country a process called after its inventor, Tesse du Motay; it is now in use by the municipal and New York gas-light companies in New York city. Water-gas, before being enriched, has a specific gravity of about one-half that of air; it has a strong odor, and burns with an almost non-luminous flame, producing an intense heat. It consists of about equal parts of hydrogen and carbonic oxide, some marsh gas, and a small percentage of car bonic acid, sulphur compounds, and any volatile impurities in the coal. After being enriched and purified it still has a strong odor and a gravity of about .66 compared with air. Its illuminating power is from 25 to 30 candles. It requires less oxygen to burn it, but will not explode as quickly as coal gas, and when exploded exerts less shock, as is shown by windows being blown out without breaking the glass. The fact that it can be produced with rapidity from smaller apparatus, and, as is claimed, more economically than coal gas, seems to indicate for it an extended use in the future.