Jon flushed once more. "Yes, that's big enough to test, I realize now. It's a good thing I waited for you to help me. I'd probably have burned myself but bad. Actually," he smiled now, "I was figuring on about a quarter of a pellet."

His father frowned. "You should have known better than that, Jon. I thought I'd taught you something about being careful, and the dangers of rashness or impulsiveness. Especially around anything as dangerous as this stuff undoubtedly is."

"You did, sir, and I'm sorry. But I forget sometimes, when I get too enthusiastic."

"Well," philosophically, "you'll probably learn as you grow older ... if you live that long!" But again there was that disarming grin, which Jon repaid in kind before leaving to get his tools and go after the mite of new metal. This time, he did not neglect his precautions. He wore his suit, and put on a pair of extra-thick, lead-impregnated gloves.

Carefully he lifted a pellet from the box, wrapped it in several layers of lead foil left after making the box. He carried it so into the storeroom, locked it in a vice, and with a fine hacksaw cut off a tiny bit. Still wrapped carefully in the lead foil, he carried the remainder of the pellet back to the box in the lock, closed the lid and then took the sample inside. He took off his suit and donned a lead-impregnated, hooded gown and the leaded gloves.

"Good," his father said when Jon told what he had done. "I think I feel well enough to sit up a bit. Suppose you crank this seat halfway up, then I can watch better while you make the tests."

"Just be sure you don't get too tired," Jon said solicitously as he raised the seat and locked it at half-recline. He had brought in another of the leaded-gowns, and he slipped this over his father's head, arms and upper torso, arranging the balance of it down over his blanket-enwrapped legs.

Then, acting on his father's various instructions, he took the particle from its wrappings and began his tests. He measured the amount of radioactivity, and together they computed its half-life.

"Wow! That sure is high-pressure stuff," Jon exclaimed when they had completed the various tests which they had the equipment to make.

His father silently motioned him to set the seat back to full recline and lay there, concentrating, for some time before he spoke.