Pyrophone (Gr.Pyrophone 140080 andPyrophone 140081 sound), or Flame Organ, a musical instrument invented by Frédéric Kastner of Paris, in which the tones are produced by flames of hydrogen or illuminating gas burning in tubes of different sizes and lengths, arranged similarly to those in the common pneumatic organ. The production of musical tones by means of the little apparatus called the philosopher's lamp, in which hydrogen gas is burned in a tube, is a popular and familiar experiment; but it has been hitherto difficult to produce the same effects with illuminating gas in consequence of the carbon element interfering with the explosions of the gases. Kastner has overcome this difficulty by burning the gas in several small jets arranged in a circle, instead of a large one. He also made the discovery that when these flames were brought together the sound ceased, reappearing as soon as they were separated, and that the position of the flames should be one third the distance from the base of the tube. By a mechanical contrivance keys like those of a pianoforte or organ are connected with jointed arms, at the end of which the flames are burned in such a manner that they may be spread apart or joined together at will by a touch of the finger.

The principles involved will be treated in the article Sound. (See also Flame).