animals if we did not give it to
them gradually," said Gurlone, with a wave of his hand. "It would kill
him, strike him down as though by invisible poison gas. His heart and
lungs would cease to function, pernicious anemia would set in, as the
red corpuscles in his blood perished by millions. He would be struck
blind, fall down and die in agony."

To Maget came the picture of the unfortunate Juan. As though answering
his unasked question, Professor Gurlone went on. "We had a peon coming
up with us," he said. "His name was Juan. He stole my sample-case,
which contained an ounce of radium chloride, and ran off with it. If
he opens it, it will kill him in just that way."

* * * * *

Maget shivered. "But--but didn't it hurt you to carry it?" he asked.

"No. For it was incased in a lead container some two inches in
thickness, and the rays cannot penetrate such a depth of lead. They
are trapped in the metal."

"Father, father, you're wasting time," broke in Kenneth Gurlone,
shaking his yellow head. "We must act at once. The peons are almost
mad with fear. Even Espinosa cannot quiet them. And every moment is
precious, for the monsters may break forth."

But Maget was looking nervously about for Durkin. Where was he? Durkin
had his mind on the treasure, and--

As they turned toward the door, the professor saying. "The rays from
the ore, which is nor so concentrated as the purified metal, do not
kill--" Durkin suddenly appeared.

He carried his rifle at his hip, and he limped and cursed angrily.
"Come across," shouted Durkin. "Give me the key to that stone house.
Snap into it, and no argument."

"The key--to the stone bank?" repeated old Gurlone.

"Yes. I'll give you five counts to throw it over--then I'll shoot you
and take it," snarled Durkin savagely. "I want that treasure, whatever
it is, and I'll have it. One ... two ... three...." The tramp sent a
shot over their heads as a warning.

"Hey, Bill, easy, easy," pleaded Maget. "That stuff is radium. It'll
ruin you, boy!"

"Shut up, you yeller-bellied bum," snarled Durkin. "Four...."

A tinkle of metal came on the stone floor of the laboratory, as old
Gurlone tossed his keys to Durkin.

"Don't go in that shack," cried young Gurlone. "It'll be your death,
man--"

"Liars," yelled Durkin, and backed out the door.

"H'm," said old Gurlone, turning to Maget. "So you came to rob us,
eh?"

* * * * *