ON ENERGY OF EONTGEN AND BECQUEREL RAYS, ETC. 
51 
If V = 6000 volts = 20 electrostatic units, then the proportion of the total loss of 
energy used up in the production of ions 
1-90 X 10-1° 1 1 
6-5 X 10-1° • 20 “ C9 
Thus quite an appreciable jDroportion of the total energy supplied is absorbed in 
producing ions. The proportion decreases with the increase of voltage. 
Distance hetween the Ions in a Molecule. 
If we suppose that most of the energy required to produce a positive and a 
negative ion from a neutral molecule is due to the work done in separating the ions 
from each other against the forces of electrical attraction, we can at once form an 
approximate estimate of the distance apart of the charges in the molecule. 
The work done in separating a charge "f- e from a charge — e, both charges 
supposed concentrated at points from a distance r to an infinite distance, is equal 
to e-/r. 
If this is equal to the energy required to produce two ions, then 
. ^ = 3-8 X 10-10, 
since e = G’5 X 10-1° 
r=:lT X IQ-o centim. approximately. 
The average diameter of an atom, calculated from various methods, is about 
3 X 10“® centim. This is a very much greater distance than the value found for the 
distance apart of the charges on the ions in a molecule. The residts support the 
theory advanced by J. J. Thomson, that ionization is produced by the removal of a 
negative ion from the molecule, and that the negative ion is only a small portion of 
the mass of the atom. The positive ion is supposed to remain attached to the rest 
of the molecule. It is to be expected from the theory that the distance of the 
charges from each other would be less than the diameter of an atom. 
The energy required to produce an ion in air is very much greater than the 
energy required to produce an ion in the electrolysis of water. If V (1’46 volts) is 
the least E.M.F. required to dissociate water, the work done in moving a quantity 
1-46 
of electricity e is Ve. The work done in producing an ion thus is Ve or X 
6‘5 X 10~i° = 3TG X 10“i" erg, or about of the energy required to produce an 
ion in air by the agency of X rays, so that in water the ions are about two atoms apart 
H 2 
