Specific Velocities of Ions in the Discharge from Points. 87 



wind-pressure by the ring; since practically the same value 

 is obtained with the embedded as with the other rings. 



Substance. 



Micro- 

 amperes. 



z in centimetres. 





Hydrogen 



3-3 

 3-2 

 32 

 1-6 

 0-8 

 3-2 

 1-6 

 32 

 3-2 



+ — 

 0-2 0-8 

 01 0-9 

 01 13 

 01 11 

 00 11 

 0-8 

 08 

 01 



10 



A. Brass ring*. 



B. I. Embedded ring. 

 B. 11. Platinum ring. 



B. III. „ 



B.'lV. Curves II." 

 B. V. „ „ 





Carbon Dioxide .. 



1-2 

 11 

 11 



-02 00 

 -006 -0-03 

 -0-2 0-0 



A. Brass ring *. 



B. I. Embedded ring. 

 B. II. Platinum ring. 



Air 



30 

 20 

 32 

 1-6 

 0-8 

 1-9 

 19 



0-3 01 

 0-00 005 

 0-2 0-1 

 01 00 



o-o 01 



o-o 01 



00 



A. Brass ring. 



B. I. Embedded ring. 

 B. II. Platinum ring. 



B. III. Impure air. 

 B. IV. Wet air. 







19 



32 

 1-6 



0-8 



02 



01 01 

 o-i 00 

 00 00 

 0-2 0-0 



B. II. Platinum ring. 

 B.III. „ 





j Turpentine 



i 



>0-9 ^0-9 



Platinum ring. 



The only other way o£ accounting for the high values of 

 z in this case is by assuming the presence in the tube of 

 ions travelling against the wind, and therefore of similar sign 

 to the ring. 



These might conceivably be liberated at the surface of the 

 ring, or else in the gas itself by the passage through it of the 

 ions from the point f. 



* In the Hydrogen and Carbon Dioxide experiments with tube A the 

 values of z are unfortunately not known to within a constant. The con- 

 stant is, however, the same for both gases ; and the closeness of the 

 agreement between the values for the brass and platinum rings in the 

 case of C0. 2 makes it probable that the constant we have assumed is 

 about correct. 



f Townsend, 'Nature,' August 9, 1900. 



