found available. A systematic search generally
reveals it somewhere in sufficient quantity to be worked. Who, then,
will be the first to discover a use for indium, germanium, terbium,
thulium, lanthanum, neodymium, scandium, samarium and others as unknown
to us as tungsten was to our fathers?

As evidence of the statement that it does not matter how rare an element
may be it will come into common use if it is found to be commonly
useful, we may refer to radium. A good rich specimen of radium ore,
pitchblende, may contain as much, as one part in 4,000,000. Madame
Curie, the brilliant Polish Parisian, had to work for years before she
could prove to the world that such an element existed and for years
afterwards before she could get the metal out. Yet now we can all afford
a bit of radium to light up our watch dials in the dark. The amount
needed for this is infinitesimal. If it were more it would scorch our
skins, for radium is an element in eruption. The atom throws off
corpuscles at intervals as a Roman candle throws off blazing balls. Some
of these particles, the alpha rays, are atoms of another element,
helium, charged with positive electricity and are ejected with a
velocity of 18,000 miles a second. Some of them, the beta rays, are
negative electrons, only about one seven-thousandth the size of the
others, but are ejected with almost the speed of light, 186,000 miles a
second. If one of the alpha projectiles strikes a slice of zinc sulfide
it makes a splash of light big enough to be seen with a microscope, so
we can now follow the flight of a single atom. The luminous watch dials
consist of a coating of zinc sulfide under continual bombardment by the
radium projectiles. Sir William Crookes invented this radium light
apparatus and called it a "spinthariscope," which is Greek for
"spark-seer."

Evidently if radium is so wasteful of its substance it cannot last
forever nor could it have forever existed. The elements then ate not
necessarily eternal and immutable, as used to be supposed. They have a
natural length of life; they are born and die and propagate, at least
some of them do. Radium, for instance, is the offspring of ionium,
which is the great-great-grandson of uranium, the heaviest of known
elements. Putting this chemical genealogy into biblical language we
might say: Uranium lived 5,000,000,000 years and begot Uranium X1, which
lived 24.6 days and begot Uranium X2, which lived 69 seconds and begot
Uranium