﻿K. H. Shellbach on Acoustic Repulsion and Attraction. 419 



pelled as long as the fork sounded. When the fork sounded 

 loudly, the light was extinguished. A gas-flarne a centimetre 

 in length fed by a narrow glass tube, when placed at the open- 

 ing of the sounding-box, split up into two tongues. Smoke 

 rising from smoking candles was also repelled. 



My earliest experiments showed that pith-balls hung on 

 threads were attracted both by sounding tuning-forks and by 

 vertical resonant plates. The above-mentioned sounding-box 

 distinctly attracted and brought into contact with itself easily 

 moveable metallic sheets and balls, even such as weighed 120 

 grammes and were at a distance of eight centimetres. 



I communicated many of these experiments as early as the 

 end of last Summer Session (zu Ende des vorigen Sommersemesters) 

 to Herr Geheimrath Magnus, who made them known to the 

 young physicists who were working with him. Herr Professor 

 Poggendorff also saw some of these experiments at my house. 

 It seems, however, that all tuning-forks have not equal power 

 to produce these phenomena ; for when last autumn I wished 

 to repeat the same experiments with other apparatus I failed. 



Hitherto, in consequence of press of business, I have been 

 prevented from continuing my experiments. Since, however, I 

 see, from No. 115 of the Proceedings of the Royal Society of 

 London, that Mr. Guthrie has performed similar experiments^ 

 I feel induced to make this preliminary communication. 



Acoustic Repulsion and Attraction. By K. H. Schellbach*. — 



No. 2. 



1 ask permission to communicate the following experiments 

 to complete those described in a previous Number of these 

 Annals. (See above.) 



Two glass flasks, each holding about 1 litre, were taken; a little 

 ammonia was poured into the one, and hydrochloric acid into the 

 other, so that their bottoms were covered to a depth of about two 

 centimetres. Both flasks were provided with doubly bored 

 corks. Atmospheric air from a gasometer was led into the am- 

 monia-flask through a tube passing through the cork and reach- 

 ing nearly to the surface of the liquid. Hence, through a con- 

 necting-tube, the ammonia entered the second flask, formed a 

 cloud of sal-ammoniac which passed up a vertical tube having 

 an upper orifice of about 2 millimetres, and rose into the air in 

 a fine stream, 2 or 3 decimetres in height. Near to the open- 

 ing of the exit- tube was placed the mouth of the sounding-box 

 before described (see 1), the fork of which gave 512 single vi- 

 brations per second. When the rising gas-stream had a mode- 

 rate (mittlere) velocity, it became divided as soon as the fork 

 * Pogg. Ann. vol. cxl. St. 2, p. 325. 



