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LIIT. Some new Experiments ivlth the Flame Tube. 

 By U. Behn* 



THE first experiments with the flame-tube were made to 

 show the change o£ air-pressure with height and for 

 some meteorological demonstrations f . Most elegantly it has 

 been used by Mr. Rubens J, and by Messrs. Kubens and 

 Krigar-Menzel § in acoustics. 



In order to obtain the maximum sensitiveness of the flame- 

 tube, which was not f ally appreciated even by Mr. Rubens J§, 

 the friction in the tube must be as small as possible. Hence 

 it has been pointed out as of first importance, that the tube 

 and the outlet holes should be wide (<?. g., tube not less than 

 5 cm. diameter and the holes '5 to 1 cm. diam.). If these 

 conditions are not fulfilled, as recently occurred ||, the sensi- 

 tiveness of the tube will of course be spoiled. 



The simple method of using the flame-tube to show the 

 change of the pressure of the atmosphere with the height 

 may be again described here. A metal tube of suitable 

 length is closed at the ends. At C (fig. 1) is an opening, 



Fiff. 1. 



connected by a flexible tube to the gas mains. A and B are 

 two holes of equal diameter (instead of having only two 

 holes, there may be a number spaced equidistantly) . Gas 

 is allowed to pass into the tube (turned over to prevent 



* Communicated by the Author. 



t U. Behn, Z. S.f. d. phys. u. chem. Unterricht, xvi. p. 129 (1903). 



X Ber. d. Deutsch. Physic. Ges. p. 351 (1904). 



§ Ann. d. Physik, xvii. p. 149 (1905). 



Regarding the theory compare Lord Rayleigh's paper "On the 

 Circulation of Air observed in Kundt's Tubes and on some allied 

 Acoustical Problems." Phil. Trans, clxxv. p. 1 (1883). 



|| P. Steindel, Z. S.f. d. phys. u. chem. Unterr. 19. 



In acoustics the best results are obtained with notes of high pitch. 

 Mr. Rubens chose, sacrificing part of the sensitiveness, the holes 

 relatively small to extend the application to notes of some hundreds 

 oscillation. 



2 U 2 



