Carbon. Water. C + 2H2O = CO2 + 4H2 And the carbon dioxide so produced interacts with more red-hot carbon, forming the lower oxide--carbon monoxide: CO2 + C = 2CO So that the completed reaction may be looked upon as yielding a mixture of equal volumes of hydrogen and carbon monoxide, both of them inflammable but non-luminous flames. This decomposition, however, is rarely completed, and a certain proportion of carbon dioxide is invariably to be found in the water gas, which, in practice, generally consists of a mixture of about this composition: WATER GAS. Hydrogen 48.31 Carbon monoxide 35.93 Carbon dioxide 4.25 Nitrogen 8.75 Methane 1.05 Sulphureted hydrogen 1.20 Oxygen 0.51 ------ 100.00 The above is an analysis of water gas made from ordinary gas coke in a Van Steenbergh generator. The ratio of carbon monoxide and carbon dioxide present entirely depends upon the temperature of the generator, and the kind of carbonaceous matter employed. With a hard, dense anthracite coal, for instance, it is quite possible to attain a temperature at which there is practically no carbon dioxide produced, while with an ordinary form of generator and a loose fuel like coke, a large proportion of carbon dioxide is generally to be found. The sulphureted hydrogen in the analysis quoted is, of course, due to the high amount of sulphur to be found in the gas coke, and is practically absent from water gas made with anthracite, while the nitrogen is due to the method of manufacture, the coke being, in the first instance, raised to incandescence by an air blast, which leaves the generator and pipes full of a mixture of nitrogen and carbon monoxide (producer gas), which is carried over by the first portions of water gas into the holder. The water gas so made has no photometric value, its constituents being perfectly non-luminous, and attempts to use it as an illuminant have all taken the form of incandescent burners, in which thin mantles or combs of highly refractory metallic oxides have been heated to incandescence. In carbureted water gas this gas is only used as the carrier of illuminating hydrocarbon gases, made by decomposing various grades of hydrocarbon oils into permanent gases by heat. Many forms of generator have been used in the United States for the production of water gas, which, after or during manufacture, is mixed with the vapors and permanent gases obtained by cracking various grades of paraffin oil, and "fixing" them by subjecting them to a high temperature; and in considering the subject of enrichment of coal gas by carbureted water gas, I shall be forced, by the limited time at my disposal, to confine myself to the most successful of these processes, or those which are already undergoing trial in this country. In considering these methods, we find they can be divided into two classes: