by this water and then pass on to the scrubbers, where they are cooled and washed by passing through a mass of coke moistened by fine streams of water. To further cleanse them they are passed through saw-dust and thence pass to the gasometer. A number of analyses made by M. Witz show that Dowson gas consists on the average of 25% hydrogen, 16 to 25% carbon monoxide, and 50% of nitrogen. The heat of combustion of one litre varies according to the quality of coal used, but averages about 1400 calories. One kilogramme of anthracite will produce about four cubic metres of Dowson gas, the cost being one-tenth of a penny per cubic metre. It must not be forgotten that this gaseous mixture is only a quarter as rich as coal gas, but it costs about one-tenth to produce, and is therefore cheaper on the whole. At some future date this type of apparatus may, to a great extent, replace the boiler of the steam engine. That Mr. Emerson Dowson’s process has succeeded beyond his most sanguine expectations goes without saying. His apparatus is in use in every corner of the globe, and, to quote his own words, “still better results can and will be obtained when an engine is really designed to give the best effect with this gas.” [Illustration: FIG. 43.—Dowson Gas-producing Plant.] _Buire-Lencauchez gasogene._—The analysis of the gas produced on this system shows that it contains 20 volumes of carbon dioxide, 115 of carbon monoxide, 66 of hydrogen, and 178 of nitrogen; its percentage composition is therefore the following:— Carbon monoxide 29·4 Carbon dioxide 5·9 Hydrogen 17·6 Nitrogen 47·1 ——— 100