Tyndall, John, 1820-1893 · London : Longmans, Green · leaf 288
apparent to youall. It will also extend the demonstration from converg-ing to diverging sound lenses. Nitrous oxide—the gas so much employed by dentists—possesses a density about equal to that of carbonic acid.This gas, which is far preferable to carbonic acid, I proposeto employ for our converging… … note of high pitch. At c is placed a sensitive flajne.The pressure is so regulated that the flame burns steadilyand tranquilly when the reed sounds. I place the soapbubble b, fig. 145, in front of the reed : the flame is throwninto stormy agitation by the convergence upon it of therays of sound.^…
Sound
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