From Experimental Results ... 'Smoke samples were collected in a small aircraft, which was flown through the smoke columns from a series of large prescribed fires in the forest areas of Western Australia in the spring of 1970. The smoke particles were deposited on air-filters or in an electrostatic precipitator, and both methods of collection gave similar results.'From Gaseous Combustion-Products ... 'It seems, therefore, that reduced visibility, resulting from smoke build-up, is the most undesirable feature of a large fire. When an extensive column of smoke has been established, a thick haze can be distributed over wide areas; but, under normal weather conditions, smoke does not persist for long, as it is spread and diluted by the wind. Since the particles are much to [sic] small to settle, it is probable that rain is the main agent for removing smoke from the atmosphere.'