Modern Gasworks Practice

700 MODERN GASWORKS PRACTICE not rendered permanently gaseous are removed. This oil is retumed to the retort again and again, the residue remaining behind. as a coke. In. this country the process has chiefly been applied in connection with the well-known Scottish shale oils, about 100 cubic feet of gas being obtained from one gallon of the oil. In countries where a mineral oil is only obtained with some difficulty the gas has been produced from animal or vegetable varieties. TYPES OF WATER-GAS PLANT The plants now in. use for the purpose of generating water gas are many and varied. In general, however, the apparatus may be classified under two distinct headings, namely :— (a) Plants employing an enriching agent, i.e. carburetting plants. (6) Plants in which. no enrichment of the gas takes place, i.e. “ blue ” gas plants. Fig. 430.—A Small Humphreys and Glasgow Installation.