PART II. POLAR MAGNETIC PHENOMENA AND TERRELLA EXPERIMENTS. CHAP. V. 657 



ithode disintegrated is proportional to the weight of those metals which would be deposited in volta- 

 eters placed in series with the discharge-tube. 



GOLDSTEIN (') has discovered that when channel rays come in contact with a metal, they cause it 

 disintegrate. If, for instance, channel rays are allowed to fall upon a gold mirror deposit on plate- 

 ass, the gold disappears from the place where the most intense rays strike, so that in a short time 

 e sheet of glass becomes transparent again. Silver and nickel also disintegrate very quickly, alumi- 

 um less so. 



According to GOLDSTEIN, cathode-rays also have the power to disintegrate metal plates, but in a 

 uch smaller degree than channel rays. 



The above-mentioned disintegration from a cathode is in all probability closely connected with this 

 ghly disintegrating effect of channel rays. 



It appears that all metals that undergo great disintegration when employed as cathodes, are also 

 sintegrated in a high degree when under the influence of channel rays. That the velocity of the metal 

 irticles flying out from the cathode must be considerable has been shown by KAEMPF by means of 

 otical investigations of double refraction by a metal mirror, produced by electric disintegration. According 

 i Kaempf, the particles expelled from the cathode are de-formed and brought into tension on striking 

 te mirror-surface. 



Up to the present, the fact of an electric or magnetic deflection of the metal particles expelled from 



!cold cathode has not been established. It is interesting, in this connection, to know that it has been 

 and that a great emission of positive ions from incandescent solid bodies is frequently accompanied by 

 ; distinctly appreciable loss of weight in the emitting bodies. 



I have myself of late made some experiments which give promise of throwing light upon the 

 i cstion of the electric charging of the metal particles thrown off from a cathode. 



The difficulty in these experiments is that if a vacuum-tube is introduced into a very strong magnetic 

 fid (as is here necessary), in such a manner that the direction of the discharge-current is perpendicular 

 t the lines of force, the character of the discharge is changed, the discharge-current being thrown to 

 ce side and concentrated in a narrow path. 



It is a different matter altogether when the vacuum-tube is placed axially in relation to the 

 rignetic field. 



The character of the discharge- current is then altered, it is true, as the cathode emits the so-called 

 ngneto-cathode rays; but, as I have already shown, under these circumstances the disintegration of the 

 chode is very great, and the discharge-current often seems to flow with normal density through the 

 etire cross-section of the vacuum-tube. 



I arranged my experiments in a manner very similar to that in which I first discovered these 

 ngneto-cathode rays( 2 ). 



A cylindrical vacuum-tube had a cathode in the form of a cross 18 mm. from the bottom of the 

 t >e, which was a plane sheet of plate-glass cemented upon it. The cross was cut out of a thin sheet 

 c palladium, its surface being parallel with the sheet of glass. The anode was circular, and was placed 

 snmetrically round the axis of the tube about 10 cm. behind the cathode. 



The vacuum-tube was placed axially in front of a powerful cylindrical electro-magnet, in such a 

 n nner that the sheet of plate-glass at the bottom of the tube was close to the end-surface of the 

 n gnet. 



') See E. GEHRCKE, Die Strahlen der posiliven Elektrizilat, p. 69. Leipzig, 1909. 

 -) See Archives cles Sciences Phys. et Nat. Geneve, June, 1896, p. 506. 



