UTAH ACADEMY OF SCIENCES 123 
energy radiated has the same value as the constant found 
in the photoelectric effect. 
It appears, therefore, that radiant energy is also in 
units which are indivisible, an idea which does not con- 
form to our usual conception of energy of wave motion. 
But the experiments indicate we have energy radiated 
and absorbed in quanta of hf. This forms the basis of 
the quantum theory. 
It is impossible to study matter without studying 
energy and vice versa. We are led to ask what is the 
structure of the atom which can absorb or radiate energy 
only in quanta of hf. This is another baffling question 
which has not been answered. We have been able only 
to skirmish a little around the edge of this field of investi- 
gation. 
When a metal surface is illuminated negative elec- 
trons are immediately shot out. The energy of emission 
in some cases is over 4,000 times as much as the atom 
could possibly have absorbed from the beam of light. 
Obviously this energy could not have come from the light. 
The electron had the energy before it left the atom. But 
we want to know how the light wave releases this energy. 
The atomic model which we construct in our minds must 
have the property of radiating energy in quanta and have 
at least one negative electron which has the energy of a 
quantum and so arranged that this energy may be 
released by a light wave. 
Let us approach the atom from another experiment. 
Radioactive substances give out negative electrons as 
well as bodies carrying positive charges. Each positively 
charged body called an alpha particle causes a charge 
equal to twice the charge of a negative electron and its 
mass is four times the mass of a hydrogen atom. These 
alpha particles are shot off from radium with sufficient 
velocity to pass thru thin sheets of metal. When a num- 
ber of alpha particles are shot thru a piece of gold foil the 
particles are scattered in a way which indicates these pos- 
itive charged bodies were being repelled by other posi- 
tively charged bodies in the gold foil. By using foil of 
other metals a scattering effect is obtained which gives a 
measure of the positive charges within the metal. When 
the positively charged alpha particle comes near a posi- 
