Steam:
Its Generation and Use

efficiency and economy of the boiler. Only one- eighth of an inch deposit of soot renders the heat- ing surface practically useless. Only one-six- teenth of an inch of scale or sediment will cause a loss of 13 per cent, in fuel. A boiler must, therefore, be kept clean, outside and in, to se- cure a high efficiency. It is never economy to force a boiler, and the best results are always attained with ample boiler power. It is also necessary to keep the boiler, always the oxygen in the atmosphere, and the other is the fuel employed. Every pound of fuel requires a given quantity of oxygen for its com- plete combustion, and thus a given quantity of air. This varies with different fuels, but in every case less air prevents complete combustion, and an excess of air causes waste of heat to the amount required to heat it to the temperature of the escaping gas. With chimney draft, the experiments of the together with its brick work, in good order, and to have careful firing where economy is desired. The result of a bad setting for a boiler has been known to be a loss of 21 per cent, in economy. Efficiency of the Furnace. Combustion may be defined as “the union of two dissimilar substances, evolving light and heat.” In ordinary practice, one of these is U. S. Navy show that ordinary furnaces require about twice the theoretical amount of air to secure perfect combustion. Prof. Schwackhoffer, of Vienna, found in the boilers used in Europe an average excess of 70 per cent, of the total amount passing through the fire — or that over three times the theoretical amount was used. A series of analyses by Dr. Behr of the escaping gases from a Babcock & Wilcox boiler, with