Smoke

Smoke is usually a gaseous current conveying solid particles in a fine state of division, If a piece of zinc be heated strongly in the air, it will catch fire and burn with a brilliant blnish flame, evolving deuse c1ouds of white smoke, This smoke is of the simplest kind. It consists of zinc oxide - often known as zinc white - which is carried upwards by the heated air. The smoke from burning fuel is of a more complex nature, although carbon in the form of soot is often present in large quantities. This is accompanied by carbon dioxide, oxygen, nitrogen, and, sometimes, carbon monoxide. In large towns the escape of large quantities of smoke into the atmosphere is considered as a nuisance, and is punishable by fine. Such an escape of smoke shows, however, that the fuel is not being consumed economically, so that it is to the consumer's interest to prevent it. To this end large furnaces are supplied with arrangements for regulating both the supply of fuel, and of air to the fire-place.