the Combustion of Gases in Tubes. 479 



But what is the state of the flame in the interval between two 

 images ? The flame of common gas, or of olefiant gas, owes its 

 luminousness to the soUd particles of carbon discharged into it. 

 If we blow against a luminous gas-flame, a sound is heard, a 

 small explosion in fact, and by such a puff" the luminousness may 

 be caused to disappear. During a windy night the exposed gas- 

 jets in the shops are often deprived of their light and burn blue. 

 In like manner the common blowpipe-jet deprives burning 

 coal-gas of its brilliant light. 1 hence concluded, that the ex- 

 plosions, the repetition of which produces the musical sound in 

 the case before us, rendered, at the moment they occurred, the 

 combustion so perfect as to extinguish the solid carbon particles, 

 but I imagined that the images on the screen would, on closer 

 examination, be found united by spaces of blue, which, owing to 

 their dimness, were not seen by the method of projection. This 

 in many instances was found to be the case. 



I was not, however, prepared for the following result : — A 

 flame of olefiant gas, rendered almost as small as it could be, was 

 procured. The 3-foot 2-inch tube was placed over it ; the flame 

 on singing became elongated, and lost some of its light, still it was 

 bright at its top ; looked at in the moving mirror, a beaded line of 

 great beauty was observed; in front of each bead was a little lumi- 

 nous star, after it, and continuous with it, a spot of rich blue 

 light, which terminated, and left, as far as I could judge, a per- 

 fectly dark space between it and the next following luminous star. 

 I shall examine this further when time permits me, but as far as 

 I can at present judge, the flame was actually extinguished and 

 relighted in accordance with the sonorous pulsations. 



When a silent flame, capable, however, of being excited by the 

 voice in the manner already described, is placed within a tube, 

 and the continuous line of light produced by it in the moving 

 mirror is observed, I know no experiment more pretty than 

 the resolution of this line into a string of richly luminous pearls 

 at the instant when the voice is pitched to the proper note. This 

 may be done at a considerable distance from the jet, and with 

 the back turned towards it. 



The change produced in the line of beads, when a tuning-fork 

 capable of giving beats with the flame is brought over the tube 

 or over a resonant jar near it, is also extremely interesting to 

 obsenre. I will not at present enter into a more minute de- 

 scription of these results. Sufficient, I trust, has been said to 

 induce experimenters to produce the effects for themselves ; the 

 sight of them will give more pleasure than any description of 

 mine could possibly do. 



and indicate alternate contractions and dilatations of the flame con-esponding 

 with the sonorous vibrations of the column of air." — F/iil. Trans., 1834, 

 p. 58C. 



