ak UTAH ACADEMY OF SCIENCES 127 
assuming that there are approximately as many electrons 
as atoms more or less free to move about in the metal— 
the electrons acting as if they were a gas and were in 
solution in the metal. Rising temperature drives some 
of them off. Those metals that are good conductors of 
electricity are also good conductors of heat, the ratios 
of the heat conductivities to the electrical conductivities 
for the metals varying from 7 to 914 x 10°. By assuming 
that heat is conducted through the metal entirely by 
these electrons, and that the electrical current consists 
of a lateral shift of these negative electrons towards the 
positive end of the metal superimposed upon their random 
motion, two equations for these conductivities have been 
obtained, and when the one is divided by the other and 
values substituted in them, the ratio comes out approxim- 
ately 6 x 10°, which agrees fairly well with the above 
mentioned values and suggests that the above assumptions 
and explanations of conduction are probably correct. 
Gases are normally almost perfect insulators, it 
requiring approximately 30,000 volts to get a spark 
across a one centimeter air gap. The conductivity 
increases with diminished pressure until very low pres- 
sures are obtained. At pressures less than 1/100 of 1 
mm. of mercury the so-called cathode stream is obtained, 
which is a stream of negative particles, called electrons 
moving toward the positive electrode with a velocity 
ranging from 1/10 to 1/2 the velocity of light. 
Gases from around flames, hot metals, arcs, phos- 
phorus, X Rays, radium, metals on which ultra-violet 
light has fallen, gases from electrolysis, gases that have 
pubbled through water, etc., are all temporary con- 
ductors of electricity. The gaseous ions may be electrons, 
atoms or molecules that have lost an electron, or either 
of these with some neutral molecules attached 
to them. When an electrical field is applied, these ions 
migrate toward the electrodes thus constituting the 
electrical current. 
