nd in his glass, still holding it up to the
light. "Indeed," he rambled on, "Treadmore babbled for Heaven knows how
long on the relative occurrence of parahydrogen and orthohydrogen on
Eisberg." He took his eyes from the glass and looked down at the girl
who was seated demurely on the edge of his bunk. Her smile was
encouraging.

"He said--and I quote"--Mike's voice assumed a gloomy, but stilted
tone--"normal hydrogen gas consists of diatomic molecules. The nuclear,
or proton, spin of these atoms--ah--that is, of the two atoms that
compose the molecule--may be oriented in the same direction or in
opposite directions."

He held a finger in the air as if to make a deep philosophical point.
"If," he said pontifically, "they are oriented in the same direction, we
refer to the substance as _orthohydrogen_. If they are oriented in
opposite directions, it is _parahydrogen_. The _ortho_ molecules rotate
with _odd_ rotational quantum numbers, while the _para_ molecules rotate
with _even_ quantum numbers.

"Since conversion does not normally occur between the two states, normal
hydrogen may be considered--"

Leda Crannon, snickering, waved her hand in the air. "Please!" she
interrupted. "He can't be that bad! You make him sound like a dirge
player at a Hindu funeral. What did he tell you? What did you find out?"

"_Hah!_" said Mike. "What did I find out?" His hand moved in an airy
circle as he inscribed a flowing cipher with a graceful Delsarte wave.
"Nothing. In the first place, I already knew it, and in the second, it
wasn't practical information. There's a slight difference in diffusion
between the two forms, but it's nothing to rave about." His expression
became suddenly serious. "I hope your information is a bit more
revealing."

She glanced at her glass, nodded, and drained it. Mike had extracted a
promise from her that she would drink one drink before she talked. He
could see that she was a trifle tense, and he thought the liquor would
relax her somewhat. Now he was ready to listen.

She handed him her empty, and while he refilled it, she said: "It's
about Snookums again."

Mike gave her her glass, grabbed the nearby chair, turned it around, sat
down, and regarded her over its back.

"I've lived with him so long," she said after a minute. "So long. It
almost seems as though I've grown up with him. Eight years. I've been a
mother to him, and a big sister at the same time--and maybe a maiden
aunt. He's been a car