246 Mr. E. Rutherford on the Electrification 



Properties of the Charged Gas. 



Since the charged gas obtained is due to the separation of 

 the oppositely charged conducting particles to which con- 

 duction in a gas under the aj-rays is probably due, we should 

 expect the positively and negatively electrified gas to closely 

 resemble Rontgenized air in its properties, and such is found 

 to be the case. 



The gas completely loses its charge in its passage through 

 the pores in a ping of glass wool ; while Rontgenized air, 

 after being forced through glass wool, loses all trace of con- 

 ductivity. 



The gas readily gives up its charge to any conducting or 

 insulating surface against which it impinges. The greater 

 amount of electrification is discharged in the passage of the 

 gas down a long tube. If the electrified air is allowed to 

 impinge against the surface of an insulated metal plate, it 

 gives up a portion of its charge to the metal. The facility 

 with which the gas is discharged is to be expected, since no 

 evidence of polarization has been found in the conduction of 

 the gas exposed to the Rontgen rays when metal electrodes 

 are used. 



A remarkable property of the electrified gas is that positive 

 and negative electrification are not discharged with equal 

 facility by all metals. When the charged gas was passed 

 through a long zinc tube, the amount of negative electrifica- 

 tion on the issuing gas was always less than the amount of 

 positive for the same velocity of the blast. By insulating the 

 zinc tube it was found that it received a greater charge of 

 negative than of positive. In order to test this difference, 

 cylinders of zinc, tin, and copper were made of the same size, 

 and the charged gas forced through them. It was found 

 that zinc and tin discharged negative electrification more 

 rapidly than positive, the difference in general amounting 

 to about 20 per cent. Copper apparently discharged the 

 positive and negative with about equal facility, but many 

 experiments seemed to point to the conclusion that even in 

 the case of copper negative was slightly more readily dis- 

 charged than positive. If the electrified gas impinged against 

 insulated plates of different metals, the same general results 

 were obtained. 



Not only was there a difference in the discharging powers 

 of positive and negative electrification for any particular 

 metal, but a copper plate, for example, discharged positive 

 more readily than a zinc plate placed exactly in the same 



