On a new Electrical Phenomenon of Motion. 533 



are better versed in scientific studies to ascertain the causes 

 and exact operations of this interesting power of the sun's rays 

 to paint the products of art, as they do so beautifully and 

 wonderfully the works of nature on the mountain, in the forest 

 and field. 



LXIX. On a new Electrical Phenomenon of Motion. 



BlJ J. C. PoGGENDORFr*. 



PHENOMENA of motion produced by the direct or indirect 

 action of electrical currents have been frequently observed, 

 and under the most varied forms ; but I am not aware that men- 

 tion has ever been made of that of which I am about to make a 

 a short report. 



The success of the electroscopic experiments, the results of 

 which I communicated, to the Academy on the 18th of March, 

 1867f, gave me occasion to observe them. Among others, I then 

 occupied myself with the excitation of electricity on rubbing 

 mercury against insulators. The enigmatical anomalies which 

 were long ago observed by the older physicists, whose observations 

 I found fully confirmed, raised the question whether they would 

 occur in the absence of air; and I thus directed my attention to 

 the phosphorus mercurialis, which in the earlier history of elec- 

 tricity played so interesting (I might almost say amusing) apart. 



With this view I had some of them made — that is, exhausted 

 tubes containing a certain quantity of mercury, and which, 

 moreover, were provided either at one end or both with platinum 

 wires for the purpose of investigating the electrical condition of 

 the enclosed mercury. 



The first tube contained only one wire. It was very luminous 

 when shaken in the dark; and when the wire was applied to an 

 electroscope, a strong divergence of the leaves ensued. The di- 

 vergence was negative, and therefore normal. 



In order to ascertain whether electrifying the tube altered this, 

 I coated it towards both ends with a broad baud of tinfoil, and 

 placed this as an exhausted double jar across the electrodes of a 

 Holtz's machine. 



The current did not in the least alter the condition of the 

 mercury; it was still negative. I thought, however, I observed, 

 while the tube lay on the electrodes, a certain motion in the 

 mercury — which, however, could have no definite character ; for 

 the current in such a jar is an alternating one. 



Hence I had another tube made provided with platinum wires 



* Translated from the Berliner Monatsberichie, June 1867. 

 t See page 549. 



