had been but momentarily explosive, they had gone off in an instant once
for all, and if there was nothing living or valuable within reach of the
concussion and the flying fragments then they were spent and over.
But Carolinum, which belonged to the beta group of Hyslop's so-called
'suspended degenerator' elements, once its degenerative process had
been induced, continued a furious radiation of energy and nothing could
arrest it. Of all Hyslop's artificial elements, Carolinum was the most
heavily stored with energy and the most dangerous to make and handle. To
this day it remains the most potent degenerator known. What the earlier
twentieth-century chemists called its half period was seventeen days;
that is to say, it poured out half of the huge store of energy in its
great molecules in the space of seventeen days, the next seventeen days'
emission was a half of that first period's outpouring, and so on. As
with all radio-active substances this Carolinum, though every seventeen
days its power is halved, though constantly it diminishes towards
the imperceptible, is never entirely exhausted, and to this day the
battle-fields and bomb fields of that frantic time in human history are
sprinkled with radiant matter, and so centres of inconvenient rays.

What happened when the celluloid stud was opened was that the inducive
oxidised and became active. Then the surface of the Carolinum began to
degenerate. This degeneration passed only slowly into the substance of
the bomb. A moment or so after its explosion began it was still mainly
an inert sphere exploding superficially, a big, inanimate nucleus
wrapped in flame and thunder. Those that were thrown from aeroplanes
fell in this state, they reached the ground still mainly solid, and,
melting soil and rock in their progress, bored into the earth. There, as
more and more of the Carolinum became active, the bomb spread itself out
into a monstrous cavern of fiery energy at the base of what became very
speedily a miniature active volcano. The Carolinum, unable to disperse,