“Can you hold it at this height for a while?” Ken asked. “I’m going to let this titanium act up here, if I possibly can. There’s atmosphere, and we’re high enough not to be visible, I should think.” Allmer gestured to the reading of the photocell.
“The door is open, and that furnace is shining pretty brightly. You’d do better to shut the door, only that would keep air pretty well out. A light like that so far from the ground must show for scores of miles.”
“I never thought of that.” Ken was a trifle startled. He thought for a moment, then, “Well, let’s close the door anyway. We have a pressure reading. If that drops, we’ll know that some sort of action is taking place.”
“True enough.” Allmer snapped the toggle closing the door and waited silently while Ken manipulated his controls. Deprived of the opening through which a good deal of heat had been radiating, the compartment temperature began to climb. By rights, the pressure should have done the same; but to Ken’s intense satisfaction, it did not — it fell, instead. At his request, the door was opened for an instant and promptly closed again; results were consistent. The pressure popped back to its former value, then fell off once more. Apparently the titanium was combining with some gaseous component of the surrounding atmosphere, though not violently enough for the reaction to be called combustion.
“If you’re far enough to one side of the beam, let’s go down to the surface,” the investigator finally said. “I’d like to find out what percentage of the air will react this way, and for any sort of accuracy I’ll need all the atmospheric pressure I can get to start with.”
Feth Allmer gave the equivalent of a nod.
“We’re a couple of miles to one side,” he said. “I can drop straight down whenever you want. Do you want the door open or closed?”
“Closed. I’ll let the sample cool a little, so we can get normal pressure after landing without using it all up. Then I’ll warm it up again, and see how much of the air in the compartment is used up.” Feth gestured agreement, and a faint whistling became audible as the torpedo began to fall without power — like the others, it had speaker and sound pickups, which Allmer had not bothered to remove. Four miles — three — two — one — with deceptive casualness, the mechanic checked the plunge with a reading of one hundred fifty feet on the altimeter, and eased it very cautiously downward. As he did so, he gestured with one tentacle at another dial; and Ken, after a moment, understood. The projectile was already below the level of the homing station.
“I suppose the transmitter is on a mountain, and we’re letting down into a valley,” Feth elaborated, without taking his eyes from his work.
“Reasonable enough — this was always supposed to be a rough section of the planet,” agreed Ken. “It’s good— there’s that much less chance of being visible from a distance. What’s the matter — aren’t you down, after all?”
The altimeter had reached zero, but nothing had checked the descent. Faint rustlings had become audible in the last few seconds, and now these were supplemented by louder snappings and cracklings. Descent ceased for a moment. Apparently an obstacle sufficient to reflect radar waves and take the machine’s weight had been encountered; but when a little downward drive was applied, the crackling progress continued for some distance. Finally, however, it ceased — noise and motion alike — even when Allmer doubled and quadrupled the power for several seconds. He opened his drive switches and turned to Ken with a gesture equivalent to a shrug.
“We seem to be down, though I can’t guarantee it’s ground as we know it. It seems to be as low as we can get, though. There’s the door switch, in case you didn’t know. You’re on your own, unless you don’t mind my hanging around to watch. I suppose the boss will be here soon, too; he should have his machine in an orbit by this time.”
“Sure — stick around. I’ll be glad to have you. Maybe we’ll have to move the thing around, for all I can tell at the moment.” He had opened the door as he spoke, and watched with interest as the pressure gauge snapped up to a value about two thirds of Sarr normal. At the same instant, the temperature dial of the still hot titanium furnace began to rise spontaneously — apparently the greater atmospheric density was more than able to offset the slight amount of cooling that had taken place; the metal was actually burning. Ken hastily shut the door.
The temperature continued to rise a short distance, while the light intensity in the cargo compartment of the torpedo held at a value that would have been intense even to eyes accustomed to Sarr’s fervent sun. The most interesting information, however, came from the pressure gauge; and it was on this that Ken kept his attention glued.
For perhaps twenty seconds the reaction continued unabated; then it began to die out, and in ten more the temperature began once more to drop. The reason was evident; pressure had dropped to less than two percent of its former value. There was literally nothing left to carry on the reaction.
Ken emitted the booming drone from his sound-diaphragm that was the Sarrian equivalent of a whistle of surprise.
“I knew molten titanium would react to completion in our atmosphere, but I didn’t think it would possibly do it here. I guess I was wrong — I was rather expecting a mixture of compounds, whose heats of formation would prevent any such reaction. Still, I suppose at this planet’s temperature, they wouldn’t have to be very stable from our point of view. .” his voice trailed off.
“Means nothing to me, but it certainly burned,” Feth
Allmer remarked. “How about your other samples? Are you going to run them off right away, or wait for things to cool down again to planet-normal?” Another dial caught Ken’s eye before he could answer.
“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.
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
