aporated instantly, like water on a hot stove.

Then he took from his pocket a small tin cup and poured out into it some
of the liquid, letting it stand a few moments, smoking.

He poured back the liquid into the flask and dropped the cup on the
hardwood floor. It shattered as if it had been composed of glass.

One of the men in the front row moved forward to pick up the pieces.

"Just a minute," interfered Kennedy. "If you think anything of your
fingers, let that be. In the rubbish, just outside the locker-room,
yesterday, I discovered the remains of a thermos bottle and of a metal
cup like this which I have dropped on the floor. I have examined the
cup, or rather the pieces.

"These two murders were committed by one of the least known
agencies--freezing, by liquid air."

I could hear a gasp from the auditors and I knew that someone's heart
must be icy at the discovery of the portentous secret.

"I have some liquid air in this Dewar flask," continued Kennedy. "That
is what liquid air is usually kept in. But it may be kept in an ordinary
thermos bottle quite well, also.

"If I should drop just a minute bit on my hand, it would probably boil
away without hurting me, for it evaporates so quickly that it forms a
layer or film of air which prevents contact of the terribly cold liquid
air and the skin. I might thrust my finger in it for a few seconds and
it would not hurt me. But if I kept it there my finger would become
brittle and actually break off, so terrible is the cold of one hundred
and ninety degrees below zero, Centigrade. It produces an instantaneous
frost bite, numbing so quickly that it often is hardly felt. Placed on
the surface of flesh this way, it changes it to a pearly-white, solid
surface. The thawing, however, is intensely painful, giving first a
burning sensation, then a stinging, flushed feeling, exactly as Irving
Evans described what he felt. The part affected swells and a crust forms
which it takes weeks to heal, supposing the part affected is small.

"Someone, in that locker-room," continued Craig, "placed a piece of
cotton soaked in liquid air on the stomach of the unconscious boy.
Instantly, before anyone noticed it, it froze through to the solar
plexus. Ultimately that was bound to kill him. And who would bear the
blame? Why, Fraser Ferris, of course. The accident in the bout afforded
an opportunity to use the stuff which the criminal in his wildest dreams
could not have bettered."

"Ho