COAGULATION OF SMOKE

Te Awamutu Courier, Volume 53, Issue 3795, 14 August 1936, Page 10

COAGULATION OF SMOKE

BY SOUND WAVES. An interesting experiment, which might conceivably have industrial applications, was the coagulation of smoke by the effect of sound waves, shown by Professor E. N. da C. Andrade, F.R.S., at the recent Conversazione of the Royal Society in London. Tobacco smoke enclosed in vertical glass tubes, was seen to coagulate rapidly when sound waves were set up in the tubes by means of a vibrating diaphragm at one end. Supersonic sound waves, with a frequency of about 220 kilocycles per second, were employed in one case and waves with an audio-frequency of 2200 cycles per second in another, both being apparently equally effective. We are informed that when the tubes are placed horizontally, the positions of the nodes and antinodes can be distinguished by differences in the rate of coagulation; they were, however, not visible in the vertical tubes. Another experiment shown by Professor Andrade was the attraction between two small spheres produced by vibration in the surrounding air when the line joining the centres of .the spheres is at right angles to the direction of propagation of the w'aves. —Engineering.