146 Messrs. Holborn and Austin on Cathode Disintegration 
Crookes’s results are given in the following table, the dis- 
integration of gold being represented arbitrarily by 100. 
Paladinmt, J, LOS 1 Brass ong os aes ee MANU og as 5 105 
Gola eae. TOG?) (Piatiaam 7. ae ian: ves ws 5'5 
Silyerics (26.2 Gan) (Copper: (sic 40 | Aluminium .. 0 
Head 6. tipo 75 | Cadmium .... 32 | Magnesium .. 0 
AN sen 2 vs eats OF.) Naekel” oak a Las 
Recently Granquist* has investigated the disintegration 
of gold, platinum, silver, and copper. The metals were used 
in the form of foil in a tube 2U cm. long and 3°5 cm. in 
diameter, in which five cathodes could be inserted by means 
of ground-glass connexions. The current from a battery of 
small storage-cells was sent for a given length of time, one 
hour or less, through one cathode at a time, the potential as 
well as the gas-pressure being kept as constant as possible 
during the time of the experiment. 
From these experiments Granquist drew the following 
conclusions :—That the loss in weight increases rapidly with 
decreasing pressure; below 0°6 mm. pressure gold appears to 
disintegrate more rapidly than the other metals, then follows 
platinum, and finally copperand silver. The last two metals, 
at any rate within the range of pressure investigated with the 
copper cathode, disintegrate in about the same degree. At 
pressures above 0°6 mm. platinum shows the greatest dis- 
integration. If the pressure of the gas be kept constant so 
that the difference of potential increases with increasing 
current, the disintegration is nearly proportional to the square 
of the current strength. Platinum cathodes heated to a red 
heat show the same disintegration as at ordinary temperatures. 
With the idea that the investigation of the disintegration 
of the cathode is of great importance for an understanding of 
the passage of electricity through gases, we have again taken 
up the investigation of the subject. 
1. Arrangement of Apparatus. 
The cathodes consisted of circular disks of metal, 1 em. in 
diameter, hung on wires of the same metal +, and were intro- 
duced by means of ground-glass connexions into the side tubes 
of the 4°5 cm. wide glass tube A (fig. 1). In order to make 
the connexions. air-tight, mercury was at first used, but was 
soon abandoned and pump-grease was substituted, since it was 
difficult to prevent small drops of mercury entering the tube 
in the frequent opening of it; and it was soon found that if the 
* G, Granquist, Ofvers. af K. Vetenskaps-Ak. Forhandl. p. 709 (1898). 
t+ Iron wire was used to suspend the cathodes of Sb, Bi, Zn, Sn, 
and Pb. 
