240 Intelligence and Miscellaneous Articles. 



nearer than the blue ; but it can hardly be conceded that the eye 

 has been modified that we should see the red pigments of a paint- 

 ing apparently nearer than the blue background. This cannot 

 be the meaning of the author ^^ hen he speaks of the disadvantage 

 of an achromatic e^ye, and when he supposes that such an eye would 

 in process of time lose its achromatism by variation and selectioji. 



ON SOME REMARKABLE PHENOMENA IN GEISSLER TUBES. BY 

 MM. REITLINGER AND VON URBANITZKI*. 



One pole of a Euhmkorff's induction-coil was connected with 

 one of the electrodes of wide cylindrical (Wiillner's) discharge- 

 tubes. The resulting alternating discharges in the tubes are divided 

 by the action of an electromagnet into two current-threads, of 

 which the one is attracted by an approached conductor, while the 

 other (which corresponds to the inflowing of positive electricity 

 into the tube), independently of the direction of the inducing cur- 

 rent, is much more powerfully repelled. The effect of this pre- 

 ponderance of the repulsion is, that without a magnet the entire 

 discharge appears to be repelled. The experiment is singularly 

 successful in carbonic acid and carbonic oxide. The negative light, 

 as already previously observed, is tolerably indifferent to the in- 

 fluencing bodies ; but with pressures below 0-2 of a millim., on 

 bringing the end of the glass tube into contact on two sides or on 

 surrounding it with the cathode, the strata of the positive light 

 move their own breadth towards the anode, so that the first of them 

 touches the anode. In oxygen this process does not make its 

 appearance. 



While the glass generally exhibits a green fluorescence at the 

 negative electrode, with the purest possible hydrogen it appears 

 greenish yellow — with oxygen, carmine red ; but in the latter, when 

 a stratum of air is inserted in the circuit, it becomes again yellow- 

 green and green. 



A vacuum-tube which did not permit the current of the induc- 

 tion-coil to pass through it at 1 centim. striking-distance, did so 

 between the poles of the magnet ; accordingly, in correspondence 

 with Hittorf's view, that which stopped the passage was situated at 

 the cathode. 



If a vertical cylindric tube be brought between the magnet-poles, 

 and thereby the positive discharge pressed threadlike, in the equa- 

 torial plane, towards the glass, and the negative bent into the 

 magnetic surface, then a third magnet-pole deflects the latter as if 

 it were paramagnetically polar, but each of the strata as if they 

 were diamagnetically polar. With alternating discharges in tubes 

 connected at one end only with the induction-coil, there appears 

 at the same wire electrode two differently coloured light-surfaces, 

 perpendicular to each other — one axial and one equatorial, the latter 

 only on one side of the wire. These phenomena cannot be deduced 

 from the known laws of the reciprocal action between current- 

 conductors and magnets. — Beihldtter zu Poggendorff's Annalen, 

 1877, No. 7, p. 416. 



* Wiener Anz. 1877, pp. 100-104. 



