“I found out something which will let me figure out what it is, very shortly,” replied Ken.
“But what did you do? Why did you go out twice?”
“You must have seen me putting a sample into the pressure bomb. I sealed it in, and brought it inside so it would all evaporate and so that the pressure gauge on the bomb would be at a temperature where I could trust it. I read the pressure at several temperatures, and weighed the bomb with the sample. I had already weighed it empty — or rather, with the near-vacuum this planet uses for air inside it. The second time I opened the door was to let off the sample, and to make a check at the same temperature with a sample of the planet’s air — after all, it must have contributed a little to the pressure the first time.”
“But what good would all that do?”
“Without going into a lot of detail, it enabled me to find out the molecular weight of the substance. I did not expect that to be very conclusive, but as it happened I think it will be; it’s so small that there aren’t many possible elements in it — certainly nothing above fluorine, and I think nothing above oxygen. I’ll concede that I may be off a unit or so in my determination, since the apparatus and observing conditions were not exactly ideal, but I don’t think it can be much worse than that.”
“But what is it?”
“The molecular weight? Between eighteen and nineteen, I got.”
“What has that weight, though?”
“Nothing at all common. I’ll have to look through the handbook, as I said. Only the very rarest elements are that light”
“If they’re so rare, maybe the stuff is not so important for life after all.” Ken looked at Drai to see if he were serious.
“In the first place,” he pointed out, seeing that the other had not been joking, “mere rarity doesn’t prove that life doesn’t need it. We use quite respectable quantities of fluorine in our bodies, not to mention zinc, arsenic and copper. This other form of life may well do the same. In the second place, just because an element is rare on Sarr doesn’t prove it would be so on Planet Three — it’s a much bigger world, and could easily have held considerable quantities of the lighter elements during its original formation, even if they had been there as uncombined gases.” The group had been walking toward Ken’s room, where he had stored most of his apparatus, as they talked. Reaching it at this point, they entered. Ken draped himself without apology on the only rack, and began to flip through the pages of the chemical handbook, in the section devoted to inorganic compounds. He realized that his mysterious substance could contain carbon, but it certainly could not contain more than one atom per molecule, so there was no danger of its being a really complex organic material.
There were, in fact, just eight elements likely to be present; and the laws of chemistry would put considerable restriction on the possible combinations of those eight. The lightest of these was hydrogen, of course; and to the hydrogen compounds Ken turned, since they came first in that section of the handbook.
Drai had moved to a position from which he could oversee the pages that Ken was reading; the less interested or less excitable Lee stayed near the door and waited silently. He was more prepared than his employer for a long wait while the scientist made his search; and he was correspondingly more surprised when Ken, almost as soon as he began reading, suddenly stiffened in a fashion which indicated he had found something of interest. Drai saw the action as well.
“What is it?” he asked at once. Both Ken and Lee realized that the “it” referred to the substance, not the cause of Ken’s interest; Drai assumed without thought that his scientist had found what he was seeking.
“Just a moment. There’s something that doesn’t quite agree — but the rest is too perfect — wait a minute—” Ken’s voice trailed off for a moment; then, “Of course. This is under normal pressure.” He looked up from the book.
“This appears to be the stuff — it’s almost completely unknown on Sarr, because of its low molecular weight— most of it must have escaped from the atmosphere eons ago, if it ever was present. According to this handbook, it should be liquid through quite a temperature range, but that’s under our atmospheric pressure. It’s quite reasonable that it should sublime the way it did in this vacuum.”
“But what is it?”
“One of the oxides of hydrogen — H2O, apparently. If it proves to be essential for the form of growth you’re interested in, we’re going to have a very interesting time handling it.”
“We have cargo shells that can be kept at outside conditions, and towed outside the ship,” Drai pointed out.
“I assumed you did,” replied Ken. “However, normal ‘outside’ conditions in the space near Planet One would almost certainly cause this stuff to volatilize just as it did from the comparatively faint heat radiating from my armor. Your shells will have to be sealed airtight, and you will, as I said, have an interesting time transferring their contents to any cave we may pick.”
Laj Drai looked startled for several seconds. Then he appeared to remember something, and his expression changed to one of satisfaction.
“Well,” he said, “I’m sure you’ll be able to figure that one out. That’s what scientists are for, aren’t they?” It was Ken’s turn to look startled, though he had known Drai long enough by this time to have expected something of the sort.
“Don’t you ever solve your own problems?” he asked, a trifle sourly. Drai nodded slowly.
“Yes, sometimes. I like to think them over for quite a while, though, and if they’re scientific ones I don’t have the knowledge to think with. That’s why I hire people like you and Feth. Thanks for reminding me — I do have a problem at the moment, on which I have spent a good deal of thought. If you’ll excuse me, I’ll attend to the finishing touches. You can stay here and work on this one.”
“There’s nothing more we can do on this planet for the present.”
“That I can believe. We’ll head back for Planet One and the rest of your laboratory facilities. Come on, Lee— we’ll leave the scientist to his science.”
Ken, unsuspicious by nature, did not even look up as the two left his room. He had just found ammonia on the list, and was wondering whether his measurement could have been far enough off to permit the true molecular weight to be only seventeen. Melting-point data finally reassured him. For safety’s sake, however, he went through all the hydrogen, lithium, beryllium, boron, nitrogen, and oxygen compounds that were listed in the handbook. The faint disturbance incident to the vessel’s takeoff did not bother him at all. The silent opening of his door made no impression on him, either.
In fact, the door had closed again with a crisp snap before anything outside the printed pages registered on his consciousness. Then a voice, coincident with the closing door, suddenly shattered the silence.
“Sallman Ken!” The mechanical speaker over the entrance boomed the words; the voice was that of Laj Drai. “I said when we parted a moment ago that I occasionally solve my own problems. Unfortunately, you have come to represent a problem. There seems to be only one solution which will not destroy your usefulness. In a way I regret to employ it, but you have really only your own unwarranted curiosity to thank. When you wake up, we will talk again — you can tell me what you think of our commercial product!” The voice ceased, with a click which indicated that the microphone had been switched off.
Ken, fully aroused, had dropped the book and risen to his feet — or rather, left his rack and floated away from the floor, since they were in weightless flight. His eyes roved rapidly to all quarters of the room in search of something that might furnish meaning to Drai’s rather ominous words. Several seconds passed before he saw it — a rectangular yellow brick, floating in the air near the door. For a moment he did not recognize it, and pushed against a wall to bring himself nearer to it; then, as he felt the chill emanating from the thing, he tried futilely to check his drift.