SMOKELESS DOMESTIC FUEL. Attention has been increasingly drawn to this subject of late years, and many organ izations have carried out useful propaganda in relation thereto. By the more scientific consumption of fuel, not only could enormous waste be obviated but the atmosphere of towns would be rendered vastly clearer and the health of the residents enhanced. (See article COAL AND COAL MINING, under Origin and Occurrences, Composition and Varieties, Chemical and Physical Characteristics.) The more bituminous a coal is, that is to say, the higher the volatile hydro-carbon content and consequently the more fuligi nous it is the more smoke it makes in burning. But even in the case of such coals, the volume of smoke in burning can be considerably reduced by mixing excess of air with the burning gases, evolved from the coal, before the temperature has fallen below the point necessary for combustion; for smoke is composed of particles of unconsumed carbon. In order to understand the reason for this we have only to realize what smoke is and how it comes to be formed. If the air feeding a fire is too limited, or the temperature too low to effect the combination of the carbon in the coal with the oxygen in the air, the atoms of carbon will combine with each other to form molecules of carbon which will collect in solid particles which it is very difficult to supply with sufficient air of a temperature high enough for combustion, and so the particles pass up the chimney with the gases (chiefly carbon dioxide) into the atmosphere. The admission of too
much unheated air also conduces to the formation of smoke by reducing the temperature of the fire.
Electricity for heating and cooking may eventually take the place of coal, but at present is too costly. The use of gas for these purposes has grown considerably of late years, and it cer tainly produces a smokeless fuel, but the use of gas has its dis advantages. The use of anthracite where burned in stoves in the house, or to afford the heat in a central heating system, has greatly increased in recent years. It can be burned with difficulty in the open grate, but is seldom so used. It burns with little or no flame and gives out great heat, but requires, for its economic application, special air feeding arrangements. "Gas" coke, i.e., coke made at gas works, because it is softer and more open than metallurgical coke, is largely used for central heating and is some times burned in the open grate, either alone or mixed with bituminous coal.
Many processes have been evolved and some carried into prac tice for providing a low temperature coke suitable for the domestic hearth, and it would appear likely that the time is not far distant when this class of fuel will be in extensive demand for heating, whether in the open grate or in stoves, and for cooking.