480 



Mr. W. Crookes on 



[Apr. 3, 



penumbra'" to increase greatly in size. Experiments recorded in the 

 paper already quoted have proved that the velocity of the molecules 

 is greater as the vacuum gets higher, and consequently the trajectory of 

 the molecules under deflecting action, whether of a magnet or of an 

 insulated idle pole, is flatter at high than at low vacua. 



An experiment is next described, having for its object to ascertain 

 whether two parallel molecular rays from two adjacent negative poles 

 attract or repel each other. It is considered that if the stream carries 

 an electric current, attraction should ensue, but if they are simply 

 streams of similarly electrified bodies, the result would be repulsion. 

 Experiment proves that the latter alternative happens, lateral repulsion 

 taking place between two streams moving in the same direction. 



Many experiments are given to illustrate the law of action of 

 magnets on the molecular stream, but the results are of too compli- 

 cated a character to bear condensation without the diagrams accom- 

 panying the original paper. 



The molecular stream is sufficiently sensitive to show appreciable 

 deflection by the magnetism of the earth. 



The author, after numerous experiments, has succeeded in obtaining 

 continuous rotation of the molecular stream under the influence of a 

 magnet, analogous to the well-known rotation at lower exhaustions. 

 Comparative experiments are given with a "high vacuum" tube, 

 where no luminous gas is visible, but only green phosphorescence on 

 the surface of the glass, and a " low vacuum " tube, in which the 

 induction spark passes in the form of a luminous band of light joining- 

 the two poles. These two tubes are mounted over similar electro- 

 magnets, the direction of discharge being in a line with the axis of 

 the magnet. Numerous experiments, the details of which are given 

 in the paper, show that the law is not the same at high as at low 

 exhaustions. At high exhaustions the magnet causes the molecular 

 rays to rotate in the same direction, whether they are coming towards 

 the magnet or going from it ; the direction of rotation being entirely 

 governed by the magnetic pole presented to the stream. The north 

 pole rotates the molecular discharge in a direct* sense, independent 

 of the direction in which the induction current passes. The direction 

 of rotation impressed on the molecules by a magnetic pole is opposite 

 to the direction of the electric current circulating round the magnet. 

 These results offer an additional proof that the stream of molecules 

 driven from the negative pole in high vacua do not carry an electric 

 current in the ordinary sense of the term. 



The author, after giving details of experiments in which platinum 

 and glass are fused in the focus of converging molecular rays projected 

 from a concave pole, describes observations with the spectroscope, 



* Like the hands of a watch. 



