FLAME FLAMEL 255 ture of oxygen with the combustible gases be- fore passing through the gauze. If one end of a small glass or metal tube, open at both ends, be introduced into the inner cone of a candle flame, and the other end elevated and a lighted taper applied to it, a second flame will be pro- FIG. 4. duced from the combustible gases which have been conveyed off by the tube. (See fig. 5.) It is by the use of such a tube, only longer, and bent so as to pass under water and into collect- ing vessels, that the gases are collected for analysis. Bunsen's burner, fig. 6, furnishes an example of the effect of a free and full supply of oxygen to a burning gas. The carbon being consumed almost simul- taneously with its hydro- gen constituent, scarce- ly any separation of sol- id particles occurs, and therefore there is but little light other than that produced by the incandescent gases and vapors. Conversely, the luminosity of a flame may be increased by the addition of substances rich in carbon. If hy- drogen gas or light car- buretted hydrogen be passed through naphtha or benzole, its flame may be rendered highly luminous. So also the addition of a substance, as chlorine gas, which has the power of abstracting the constituent hydrogen from a carbo-hydrogen gas and set- ting free the carbon, will increase the luminos- ity of a flame. Increase and diminution of pressure have been found by Frankland to have a remarkable influence upon the luminosity of flames. On the summit of Mont Blanc candles burn with a feeble light, and in artificially rarefied air it has been found that the bright- ness of ordinary flames increases or diminishes in proportion to the increase or diminution of pressure, down to that which supports a column of mercury of 14 inches. Below this pressure the luminosity diminishes at a less rate than the pressure. Under increased pressure a 324 VOL. VIL 17 FIG. fl. flame fed with amylic alcohol was found to in- crease in direct proportion to the pressure till it was equal to two atmospheres, and beyond this the light increased more rapidly than the pressure. The increase of light is caused by the greater separation of carbon particles un- der increased pressure, the incandescence of which is the cause of the light. Under a pres- sure of two atmospheres candle flames evolve much smoke ; and the flame of alcohol, which is ordinarily very pale, becomes highly lumi- nous under a pressure of four atmospheres. Conversely, flames which smoke in an ordinary atmosphere cease to do so in a rarefied one, the combustion being more complete in consequence of the greater mobility of the gaseous particles. The reason why the luminosity of flames in very rare atmospheres does not decrease in exact proportion to diminution of pressure is that the incandescent carbon does not furnish all the light ; the remainder, which amounts to about 1 per cent, under ordinary circumstances, being produced by incandescent gas, and not being affected by pressure, adding a greater proportional fraction to the amount. Singing flames were partially investigated by De la Rive in 1802. A small quantity of water heated in the bulb of a thermometer pro- duced musical sounds by the periodic expansion and condensation of vapor in the tube ; and he referred the singing of ordinary gas flames in tubes to a similar expansion and condensation of the aqueous vapor formed by the combus- tion. Faraday, however, in 1818 showed that flames which did not produce water in burning, such as that of carbonic oxide gas, would pro- duce musical sounds ; and that they would also occur in ordinary flames when the surrounding air was raised above 212 F., so that no con- densation of vapor could take place. Experi- ments in which flames are subjected to the in- fluence of acoustic vibrations producing musi- cal tones show conclusively that the notes pro- duced by them are not of that independent character which would result from expansion and condensation of vapor, but that they have an intimate relation with the principles of har- mony. The influence which the length and calibre of the tube in which the combustion takes place, being precisely of the same kind as that exerted on a jet of air blown into an organ pipe, and the sensitive manner in which flames respond to certain musical tones (as has been beautifully illustrated in experiments by Tyndall), indicate their relation to and depen- dence upon the acoustic vibrations which pro- duce these tones. This subject, and also that of Konig's sensitive manometric flames, which pulsate on receiving musical vibrations under circumstances in which they indicate by their forms the nature of the sounds, will be treated of in the article SOUND. FLiMEL, Nicolas, a French scribe and repu- ted alchemist, born about 1330, died in Paris, March 22, 1418. He combined the occupations of copyist and bookseller, married Pernelle, a
