“Hey — who lit the sodium?” he asked, heedless of Allmer’s query. “It’s cooling now, but it must have been burning, too, for a while when there was air.”
“Let more in and see.” The toggle snapped over, and there was a distinct popping sound as air rushed into the rear-vacuum. The sodium continued to cool.
“Maybe a spark from the titanium pot lighted it up.” Without answering, Ken closed the door once more and began to warm up the sodium container. Apparently Feth’s suggestion was not too far from the mark; very little additional heat was needed to ignite the metal. This time the reaction stopped after pressure had dropped about a sixth. Then the door was opened again, and another touch of artificial head caused the reaction to resume. This time it continued, presumably, until the sodium was consumed.
“I want enough material to work on when we get it back,” Ken explained. “I’m not the Galaxy’s best analytical chemist.”
The crucible of carbon dust gave decidedly peculiar results. Something certainly happened, for the material not only maintained but even increased its temperature for some time after the heating current was cut off; but there was no evidence either of consumption or production of gas in the closed chamber. Both Ken and Feth were slightly startled. The former, in response to the mechanic’s quizzical expression, admitted the fact was probably significant but could offer no explanation.
Samples of iron, tin, lead, and gold followed in due course. None of these seemed greatly affected by the peculiar atmosphere at any temperature, with the possible exception of the iron; there the pressure drop was too small to be certain, since in each of these cases the heating had caused an increase in pressure which had to be allowed for. Magnesium behaved remarkably like sodium, except that it burned even more brightly than the titanium.
Here again Ken decided to finish off the metal by relighting it with the door open; and here the testing program received a sudden interruption.
Both Sarrians were perfectly aware that with the door open a beam of light must be stabbing out into the darkness. Both had ceased to worry about the fact; it had been equally true, though perhaps the radiance was fainter, with the blazing sodium and almost as much so when the sheer heat of the samples of iron and gold had been exposed. They had completely ceased to worry about being seen; a full hour had already passed since they had landed the torpedo, owing to the cooling periods necessary between tests, and there had been no sign that any attention had been attracted. Ken should have remembered the difficulty that had been encountered in reaching the ground.
The possibility was brought back to their attention with the relighting of the magnesium sample. As the photocell reported the reestablishment of combustion, a shrill sound erupted from the speaker above the control board and echoed through the ship. Neither had to be told what it was; both had heard the recordings of the voice of the Third Planet native who had found the original torpedo.
For an instant both remained frozen on their racks, exploring mentally the possibilities of the situation. Feth made a tentative gesture toward the power switches, only to be checked by an imperious snap of Ken’s tentacles.