386 
5.760.400. 200, 2,3 . 104 
“P= 15380908. 10-54 
This amount for Ap is considerably greater than the experimen- 
tally found value (viz. about [0.08| mm.) with the substituted value 
of p. That the calculation gives a result that deviates from the value 
determined experimentally was only to be expected, seeing the 
arbitrary character of the suppositions. When e.g. in the beginning 
of § 5 sub 6 we had changed our assumptions in that sense that 
on discharge of the positive ions not 50°/,, but only 15°/, less 
molecules are formed, then on transition of the negative ions into 
the “neutral” gas state, we should have found for the calculated 
pressure effect a value of [0.087] mm., which practically would have 
— 335,5 baryes — [0,29 mm. | 
been in agreement with the empirically found value. 
c. However even the supposition that an equal number of negative 
and of positive ions take part in the conveyance of the current, will 
not correspond with reality. As will be shown presently, we should, 
bowever, have arrived at similar results, when it had e.g. been 
assumed that per positive ion an equal number of gas molecules 
are formed on discharge as per negative ion, but that a much greater 
part of the current-conveyance takes place by the negative ions 
than by the positive ones '). 
There is, indeed, a certain ground for the supposition that a 
greater part of the current conveyance takes place through the 
negative ions than through the positive ones. 
In the paper cited by us (BoLtzmann-Festschrift 1904) Stark already 
used the formula V,=1,37 X V, for air, when the positive and 
the negative ions are ‘“molecule-ions’, in which formula V, and 
V, are the different specific velocities of the negative and the posi- 
tive ions. Also Ratner (Phil. Mag. (6) 32, 441, 1916) uses this 
value for normal cases, pointing out, however, that on change of 
the gas pressure and of the electric force, this quantity does not 
remain constant. When we assume the value 1,3 for the ratio 
V5 
Vp 
negative ions, and for 43,5 °/, through the positive ions 
100 
a | 
(Ga = ) 
Among the circumstances described in this § 5 under c we find 
, the current conveyance takes place for 56,5 °/, through the 
') It is further plausible that the too high result is owing to the fact that also 
in the pressure region considered here for a great part free electrons will reach 
the anode. This will be further discussed presently. 
