Genesis of Ions by the Motion of Positive Ions. 749 
p Xa for air and hydrogen. The points marked with small 
circles are those determined experimentally, and those marked 
with a cross are the theoretical values of the quantity X xa. 
800 
a 3 s 
Sparking potentials in Volts [Vand a xf | 
8 
a 
S 
i=) 
! 2 3 4 5 6 
axp [@ m centimetres, p in rmillemetres of Mercury.) 
Fig. 3 
700 
6oc. 
500 
400 
Sparking potential in Volts |V and aX | 
200 
eee 
6 8 10 12 
4a 
ax pp a mreasusea Ti cerlt7zelres 
ve) milterzetres, of Mercury 
z 
{t has already been pointed out that the potential X xa is a 
function of the quantity of gas between the plates which s 
proportional to the product p x a. 
Phil, Mag. 8. 6. Vol. 8. No. 48. Dec. 1904. Aad 
