No. 53 197. 



Propagation, Velocity, Pressure-Variation, Reflection, Refraction of Sound. 



419 



53 193. 1 : 2. 



53 197. 1 : 8. 



53 194. 1 : 24. 



53 196. 

 1 : 25. 



53.188. Sensitive Flame, after Rebenstorff, generating its own gas (Ztschr. f. d. phys. u. chem. 

 U. 19, 1906, p. 281) 



The apparatus is fed with a mixture of equal parts of ether and benzol; the gas issuing from 

 the burner nozzle becomes mixed with air and is ignited above the net. The sensitivity can be altered 

 by regulating the air current by means of the rubber bellows. The differences in sensitivity on pro- 

 nouncing different vowels can be shown. 



53.189. Air Concussion Apparatus (Fr. phys. Techn. I, 2, Pig. 3708 [I, Fig. 668]), Figure, 

 funnel-shaped with drum-stick 



53.190. - - idem, after Weinhold (W. D. Fig. 199 [184]), cylindrical, with drum-stick . 



53.191. Kundt's Manometer with stopcocks, after Trussevitch, Figure, with funnel and 

 indicator for the air currents, on stand (Fr. phys. Techn. I, 2, Figs. 3711 and 3735) 



The flap valve, formed of a fish-bladder membrane, is placed inside a tight-fitting conical stop- 

 cock. By turning the stopcock through about 180 the valve can be used as a pressure or suction valve. 

 The pointer shows the direction in which the flap opens. The apparatus should be connected, by 

 means of a length of rubber tubing to be attached, with a suitable manometer, e. g., Kolbe's Thermo- 

 scope. The apparatus is peculiarly adapted for Rostovzev's experiment on the reflection of sound waves 

 (Ztschr. f. d. phys. u. chem. U. 16, 1903, p. 288), in conjunction with two concave mirrors and the 

 pipe No. 53,192. 



53.192. Tuned Pipe for above, on stand, Figure (Fr. phys. Techn. I, 2, Figs. 3726 and 3735) 



53.193. Apparatus for showing the Pressure Change in Sound Waves, after Szymanski, 

 Figure (Ztschr. f. d. phys. u. chem. U. 1, p. 148; W. D. Fig. 201 [186]) . . . . 



52,730. Pressure Level, after Topler, Figure 52,730, p. 368 (W. D. Fig. 141 [187]) . . 



53.194. Tyndall's Apparatus for showing the Propagation of Sound in Long Tubes, Figure 

 (Tyndall, Sound [der Schall], Fig. 4; Fr. phys. Techn. I, 2, Fig. 3709 [I, Fig. 669]), with 

 telescopic sheet iron tube 3 m long, with supports 



53.195. Drawn Brass Tube, after Eebenstorff, for demonstrating the conservation of the 

 density of sound without lateral propagation (Ztschr. f. d. phys. u. chem. U. 19, 1906, p. 279), 

 as well as for thermal expansion in large dimensions (Ztschr. f. d. phys. u. chem. U. 

 20, 1907, p. 248); total length 4 m; width 20 mm; in two parts, for heating by steam 



s. d. 

 18.0 



10.0 

 9.0 



1. 0.0 



0. 12. 



0. 

 0. 



9.0 

 5.0 



1. 4.0 



