Intelligence and Miscellaneous Articles. 551 



tubes and the so-called electrical egg. Already, when using also 

 the double-barrelled valve air-pump, we had experimented with an 

 electrical egg and atmospheric air and seen a distinct recession of 

 the visible luminous swell in the centre of the egg as the hand was 

 brought nearer from a distance. With five or more centims. dis- 

 tance between the hand and the glass wall of the egg the retreat 

 was very evident ; but on the glass being touched, it was changed 

 into an attraction, at least in appearance. When we experimented 

 with the Geissler air-pump and the wide tube above-mentioned, 

 there appeared first, when the induction-current passed through in 

 the usual manner, altogether similar phenomena as in Wiillner's 

 tubes ; in particular here also with greater rarefaction the attrac- 

 tion changed into repulsion. But the most striking repulsions 

 were obtained when only one pole of the Ruhmkorff apparatus was 

 connected with one of the wire electrodes of the tube, and the 

 other was led away to earth. In this case a luminous appearance 

 was perceptible, which, of course, shone brighter only with a 

 higher degree of rarefaction ; but it then exhibited the repulsion- 

 phenomenon especially distinct and with a distance of several 

 centims. between the hand and the glass tube. Its appearance 

 was essentially different, according as the positive or the negative 

 pole of the induced open current was connected with the wire ; 

 and the strength of the repulsion was also in the hitter case much 

 more considerable than in the former. This repulsion increased 

 as the rarefaction was pushed further, and was most intense at 

 the highest degree of rarefaction attained, about 0*2 millim. The 

 singularly favourable result of this experiment induced us to put 

 the wire electrode ef the tube into conducting connexion with the 

 conductor of a two-disk Winter electrical machine ; and in this 

 case also, with very strong rarefaction, the positive luminous tuft 

 was seen to recede. Experiments for the purpose of testing the 

 principal inferences suggested by the phenomena with the unclosed 

 current are already in preparation. This may also be the place to 

 mention that in none of the cases investigated by us did an ebonite 

 plate when brought near attract or repel. 



The striking similarity which is shown between the luminous 

 phenomenon in the unclosed current with great rarefaction and 

 the figures of comets, and the great distance at which in this case 

 the repulsion of the approaching conductor yet acts, reminded us 

 afresh of the question (touched upon in our first communication) 

 whether, in the repulsion under consideration, we have not to do 

 with that very force which makes the tails of comets recede from 

 the sun. That the degrees of rarefaction at which the best results 

 are here obtained lie near 0*2 millim. is only favourable to such an 

 assumption. Further, in those Geissler tubes in the collection of 

 the Second Physical Lehrkanzel in which the recession of the 

 electrified luminous gas-columns before the approaching conductor 

 was first observed, the light which appeared, when examined with 

 the spectroscope, showed distinctly upon a less-bright background 

 those three spectral bands which the spectroscope exhibited also 

 in the flame of illuminating-gas, and which are usually designated 



