"Keep it hot!"

He squirmed. His space suit was fabric, like the rest, but it had been
cut down to permit him to use it. It was bulkier on him than the suits
of the others. He shifted his shoulder pack. The brass valve-nipple by
which the oxygen tank was filled....

He jammed a ragged fragment of tin in place. He pressed down fiercely. A
blazing jet of fierce, scintillating, streaking sparks leaped up from
the spot where the metal glowed brightly. A hollow in the metal plate
appeared. The metal disintegrated in gushing flecks of light....

White-hot iron in pure oxygen happens to be inflammable. Iron is not
incombustible at all. Powdered steel, ground fine enough, will burn if
simply exposed to air. Really fine steel wool will make an excellent
blaze if a match is touched to it. White-hot iron, with a jet of oxygen
played upon it, explodes to steaming sparks. Technically, Mike had used
the perfectly well-known trick of an oxygen lance to pierce the airlock
door, let the air out of the lock, and so allow the outer door to be
opened.

There was a rush of vapor. The door was drilled through. Haney picked
Mike up bodily, Joe heaved the door open, and Haney climbed into it,
practically carrying Mike by the scruff of the neck. Joe panted, "Plug
the hole from the inside. Sit on it if you have to!" and slammed the
door shut.

They waited. Sanford's voice came in the ear-phones. It was higher in
pitch than it had been.