Of course, at that time the members of the expedition did not understand the conditions of Mercury as they are now known.  They had to depend upon the general impression they got from their first-hand investigations; and it is remarkable that the doctor should have guessed so close to the truth.

“He must have made up his mind to outlast everybody else,” was the way he put it as he kicked off his suit.  He stepped up to the cabinet and felt of the glass.  “I wish it were possible, without breaking the case, to see how he was embalmed.”

His fingers still rested on the glass.  Suddenly his eyes narrowed; he ran his fingers over the entire surface of the pane, and then whirled to stare at a thermometer.

“That’s mighty curious!” he ejaculated.  “This thing was bitter cold when we brought it in!  Now it’s already as warm as this car!”

Smith’s eyes lit up.  “It may be,” he offered, “that the case doesn’t contain a vacuum, but some gas which has an electrical affinity for our atmosphere.”

“Or,” exclaimed the geologist suddenly, “the glass itself may be totally different from ours.  It may be made of—­”

“God!” shouted the doctor, jerking his hand from the cabinet and leaping straight backward.  At the same instant, with a grinding crash, all three sides of the case collapsed and fell in splinters to the floor.

“Look out!” shrieked Jackson.  He was staring straight into the now unhooded eyes of the giant.  He backed away, stumbled against a stool, and fell to the floor in a dead faint.  Smith fumbled impotently with a hammer.  The doctor was shaking like a leaf.

But Van Emmon stood still in his tracks, his eyes fixed on the Goliath; his fingernails gashed the palms of his hands but he would not budge.  And as he stared he saw, from first to last, the whole ghastly change that came, after billions of years of waiting, to the sole survivor of Mercury.

A glaze swept over the huge figure.  Next instant every line in that adamant frame lost its strength; the hardness left the eyes and mouth.  The head seemed to sink lower into the massive shoulders, and the irresistible hands relaxed.  In another second the thing that had once been as iron had become as rubber.

But only for an instant.  Second by second that huge mountain of muscle slipped and jellied and actually melted before the eyes of the humans.  At the same time a curious acrid odor arose; Smith fell to coughing.  The doctor turned on more oxygen.

In less than half a minute the man who had once conquered a planet was reduced to a steaming mound of brownish paste.  As it sank to the floor of the case, it touched a layer of coarse yellow powder sprinkled there; and it was this that caused the vapor.  In a moment the room was filled with the haze of it; luckily, the doctor’s apparatus worked well.

And thus it came about that, within five minutes from being exposed to the air of the sky-car, that whole immense bulk, chair and all, had vanished.  The powder had turned it to vapor, and the purifying chemicals had sucked it up.  Nothing was left save a heap of smoking, grayish ashes in the center of the broken glass.