126 =-s«2Z.. Boboulieff—Dissipation of Electricity in Gases. 
As the result of these considerations we must admit that 
during the slow dissipation of the eaery the number of —_ 
dropping on the surface of the electrified body is nearly such a 
as determined by the pressure and temperature of the gas pie 
nearest to the surface. 
According to Maxwell* the number of atoms adhering in a 
given unit of time to a given unit of surface is 
where / and u are . 4 mean hs of path and the 
mean velocity of the atom; N is the number of atoms in the 
unit of volume of the gas; z is the codrdinate whose axis is 
normal to the surface; n, an abstract a epg either whole or 
fractional, included between zero and in nity. 
The number of atoms falling in the elementary —_ of time 
dt on the element ds of the oneag of the body will be 
= dt; 
hence the number of atoms See in the time dé on the 
whale surface of the sphere R will be : 
a NuR? dt. 
Each atom on striking the sphere will receive a quantity g of 
electricity, expressed by the ae 
1? 
bee Tr aS 
consequently the ball in the time dt will lose a quantity of 
electricity equal to 
Nu Qr dt; 
that is to say, 
dQ=—— NuQr dt; 
whence, assuming N and ~ to be constant, we obtain by inte- 
gration ‘the formula of Coulomb: 
ess 
in which the coefficient of dissipation will be 
3 
— 7 Nur 
= 
* Maxwell, Illustrations, Phil. Mag., vol. xix, p. 29. 
+ Reiss, Reibungs wena 09 vol. i, p. 226. 
