"That's why I won't let them in, Hardwick. Our storage tanks go down to bedrock. The leaked fuel--warmed up, now--is seeping along bedrock and eating at other tanks, besides being absorbed generally by the soil and dissolving in the ground-water. We've pulled all personnel out of all the area it could have seeped down to." Hardwick felt slightly cold at the back of his neck. "I suspect," he said wryly, "that they came out on tiptoe, holding their breaths, and that they were careful not to drop anything or scrape their chairs when they got up to leave. I would have! Anything, of course, could set it off. But it is bound to go anyhow! Of course! Now I see why we couldn't make a rocket-landing!" * * * * * The chilly feeling seemed to spread as he realized more fully. When ship-fuel is refrigerated during its manufacture, it is about as safe a substance as can be imagined--so long as it is kept refrigerated. It is an energy-chemical compound, of atoms bound together with forced-valence linkages. But enormous amounts of energy are required to force valences upon reluctant atoms. When ship-fuel warms up, or is catalyzed, it goes on one step beyond the process of its manufacture. It goes on to the modification the refrigeration prevented. It changes its molecular configuration. What was stable because it was cold becomes something which is hysterically unstable because of its structure. The touch of a feather can detonate it. A shout can set it off. It is, indeed, burned only molecule by molecule in a ship's engines, being catalyzed to the unstable state while cold at the very spot where it is to detonate. And since the energy yielded by detonation is that of the forced bonds ... why ... the energy-content of ship-fuel is much greater than a merely chemical compound can contain. Ship-fuel contains a measurable fraction of the power of atomic explosive. But it is much more practical for use on board ship. The point now was, of course, that leaked into the ground and warmed ... why ... practically any vibratory motion will detonate it. Even dissolved, it can detonate because it is not a chemical but an energy-release action. "A good, drumming, heavy rain," said Sandringham very calmly indeed, "which falls on this end of the island, will undoubtedly set off some scores of tons of leaked ship-fuel. And that ought to scatter and catalyze and detonate the rest. The explosion should be equivalent to at least a megaton fusion bomb." He paused, and added with irony, "Pretty situation, isn't it? If the civilians hadn't irrigated, we could evacuate Headquarters and let it blow--as it will anyhow. If the fuel hadn't leaked, we could let in the civilians until the island's soil decides what it's going to do. Either would be a nasty situation, but the combination--" Werner said shrilly: