The New York herald., 1922-07-02

member of the American Physical
Society; he tcas graduated at the
College of Wooster In 1908, received
the degree Of N. S. from Wooster In
1909 and the degree of Phi. d. from
Princeton In 1912.
1 BY KARL TAYLOR COMPTON,
Professor of Physics in Princeton
University.
| Within the last twenty-fi Ave years
and chiefly within the last ten years
definite proof of the existence of atoms
and molecules has been found anc
methods have been developed to count
and weigh them individually with very
significant results. More important
still. it has been shown that all atoms
are themselves built out of still smaller
and more fundamental units of mat
ter, electrically charged, called positive
electrons and negative electrons
There is very decisive evidence of the
existence of these two fundamental
types of matter, and OF the number
of. each type in any given kind OF
atom. To this extent the "electron
theory of matter" is no longer to be
considered as theory but as a fact
But when we attempt to explain all
the physical and chemical properties
of matter as due to these electrons
and the electromagnetic forces be-
tween them we encounter some sur
prising and unexpected facts regard
ing the behavior of electrons when in
fiuenced by other electrons or by
radiation, so that this is still a field of
hypothesis and experimentation.
When an electric discharge at sew
eral thousand volts Is passed between
two metallic electrodes sealed into a
glass vessel from which most of the
air, or other gas, has been pumped
the remaining gas and the walls of
the glass vessel become luminous.
This luminosity is of different sorts
in different parts of the vessel and
can easily be shown to be due to two
different agents. One of these con-
sists of something shooting out from
the cathode. or negative electrode, and
producing luminosity In everything in
it's path. The other consists of some
thing shooting out from the anode and
moving toward the cathode, also pro-
ducing luminosity of gas molecules or
other objects in its path but luminos-
ity of different color from that pro-
duced by the stream from the cathode.
The so-called cathode rays are found
to consist of a stream of negatively
charged particles, as is proved by the
fact that their paths are bent If placed
In an electric or magnetic field, or by
the fact that If they are caught in a
metallic cup this cup receives a charge
of negative electricity. From the
amount of bending in electric and
magnetic fields of known strength,
which may be seen by the luminous
trace of the path Of the stream along
properly placed fluorescent plate, it
is possible to calculate the speed Of the
particles and the ratio of their charge
to their mass, denoted by elm. The
speed of the particles depends upon
the voltage applied to the discharge
tube, but the value of elm does not
depend on the voltage or the kind of
gas in the vessel or the material 0f
the electrodes. 1t is n definite corl-
slant about 1916 times larger than the
ratio of the charge to the mass of hy-
drogen ions liberated by electrolysis.
Thus, if the charge on one of these
particles is equal to the charge on a
hydrogen ion Gas we shall see is the
case), then these particles must be
1916 times lighter than hydrogen
atoms. These particles, which consti-
tute the cathode rays. are the mega
tive electrons. They may be driven
out Of metals by raising the tempera-
ture, or by exposing to ultraviolet light
or X-rays. or by intense lombard
ment, or by chemical actions, &C.
Their properties, as regards mass and
charge, are the same howeveS they are
liberated, and they must be considered
as one of the fundamental units of
which matter is composed.
Magnetic and Electric Fields
n1d1~x ,.,-