Smoke

a vaporous mixture discharged from a fire. Damp fuel gives more smoke than dry fuel. The American Indian who wished to escape observation made his campfire only of the driest wood. The dark color of smoke is due to unconsumed particles of fuel, that is to say, of carbon. When a lamp smokes, the oil is vaporizing before it is entirely consumed. In case of perfect combustion, the gas which escapes from a chimney or smokestack is invisible. Black smoke is certain evidence that a part of the fuel is escaping into the atmosphere. Despite a public belief to the contrary, railroad managers have an eye to the color of the smoke made by their employes. A fireman on an engine that habitually emits black smoke is regarded as a fit subject for reproof or instruction.

The smoke nuisance is a serious matter in manufacturing cities and near railroad yards. From a scientific point of view, the heavy column of black smoke that issues from many a smokestack is wasteful, unnecessary, and unpardonable. Coal gives rise to more complaint than wood. Theoretically, if coal be heated to a white degree before it is ignited, and be supplied with the right proportion of atmospheric air, it will not smoke-that is to say, hot coal and the right draught create no black smoke. Many devices have been proposed to obviate the smoke nuisance. One of these is an endless chain apron, which advances about an inch a minute, on which coal is sent to the fire. As the coal approaches the fire, it is heated to a high degree, which, with proper control of the draught, gives, it is claimed, perfect combustion and consequently no smoke.