174 MM. Kundt and Rontgen on the Electromagnetic 



On account of the interest presented by the question whether 

 this property does not belong to gases in general, we resolved 

 to repeat the experiments once more with the most powerful 

 currents and, in all other respects, under the most favourable 

 conditions ; and we have now succeeded in verifying the 

 phenomenon sought, at least for the vapour of bisulphide of 

 carbon. 



We selected this substance for the experiments because, on 

 the one hand, in the liquid state it exhibits an energetic elec- 

 tromagnetic rotation, and, on the other, its vapour possesses 

 considerable tension even at comparatively low temperatures. 



The apparatus employed for enclosing and heating the 

 carbon bisulphide is delineated in fig. 3, PI. VIII., one tenth 

 of its actual size. An iron tube, a a, is furnished at its ends 

 with two strong conically out-turned brass collars, b b ; into 

 these two brass pieces, c c, likewise conical, can be inserted, 

 and each pressed in firmly by means of six strong screws. 

 The inserted pieces are perforated in the direction of the length 

 of the tube (diameter of the perforations 1 centim.) ; and to 

 the side turned towards the interior of the tube two glass 

 plates, d dj 1 centim. thick, are cemented, which are also held 

 by strong screws. To the insertion-pieces, c, two tin-plate 

 tubes, e e, are screwed ; and the whole is enclosed in the tin- 

 plate tube//, in the centre of which it is held by the two 

 corks g g. The tubes e e stand out about a centimetre beyond 

 the corks. By an inlet-tube, h, in one of the corks, steam can 

 be introduced into the space between the iron tube and the 

 surrounding tin-plate tube ; through a tube, i, in the other 

 cork it can pass out again. Consequently the iron tube could, 

 by steam led round it, be heated in its entire length to 100°. 

 The outer tin-plate tube was enclosed in six large coils of 

 wire. 



The wire was of 3 millims. thickness. ; in each coil there 

 were about 400 turns, through which the current of 64 large 

 Bunsen cells could be sent. 



For the experiment some bisulphide of carbon was poured 

 into the iron tube, and the air expelled by the carbon- bisulphide 

 vapour already forming at the ordinary temperature. Then 

 the inset pieces were screwed as fast as possible to the ends, 

 the tube with its appendages was fixed in its place inside the 

 wider tin-plate tube .and the spirals, and steam introduced. 

 As soon as the entire tube had acquired the temperature of 

 boiling water, all the mist that had appeared on the glass 

 plates during the heating vanished, and the plates and the 

 sulphide-of-carbon vapour that had formed in the tube were 

 perfectly transparent. A rectilineal pencil of light, polarized 



