"Queer," he said. "You think of the damage forty tons of ship-fuel can do. Setting off the rest of the store and all. But even by itself it rates some thousands of tons of TNT. I wonder what TNT was, before it became a ton-measure of energy? You think of it exploding in one place, and it's appalling! But think of all that same amount of energy applied to square miles of upside-down swamp. Hundreds or thousands of miles of upside-down swamp. D'you know, lieutenant, on Soris II we pumped a ship-fuel solution onto a swamp we wanted to drain? Flooded it, and let it soak until a day came with a nice, strong, steady wind." "Yes, sir," said Barnes respectfully. "Then we detonated it. We didn't have a one per cent solution. It was more like a thousandth of one per cent solution. Nobody's ever measured the speed of propagation of an explosion in ship-fuel, dry. But it's been measured in dilute solution. It isn't the speed of sound. It's lower. It's purely a temperature-phenomenon. In water, at any dilution, ship-fuel goes off just barely below the boiling-point of water. It doesn't detonate from shock when it's diluted enough to be all ionized--but that takes a hell of a lot of dilution. Have you got some more coffee?" "Yes, sir," said Barnes. "Coming up, sir." "We floated ship-fuel solution over that swamp, Barnes, and let it stand. It has a high diffusion-rate. It went down into the mud--And there came a day when the wind was right. I dumped a red-hot iron bar into the swamp water that had ship-fuel in solution. It was the weirdest sight you ever saw!" Barnes served him more coffee. And Hardwick sipped it, and it burned his tongue. "It went up in steam," he said. "The swamp water that had the ship-fuel dissolved in it. It didn't explode, as a mass. They told me later that it propagated at hundreds of feet per second only. They could see the wall of steam go marching across the swamp. Not even high-pressure steam. There was a _whoosh!_ and a cloud of steam half a mile high that the wind carried away. And all the surface water in the swamp was gone, and all the swamp-vegetation parboiled and dead. So"--he yawned suddenly--"we had a ten-mile by fifty-mile stretch of arable ground ready for the coming colonists." He tried the coffee again. He added reflectively: "That trick--it didn't explode the ship-fuel, in a way. It burned it. In water. It applied the energy of the fuel to the boiling-away of water. Powerful stuff! We got rid of two feet of water on an average, counting what came out of the mud. It cost ... hm-m-m ... a fraction of a gram per square yard." He gulped the coffee down. There were men looking at him solicitously. They seemed very glad to see him awake again. There was a monstrous bank of cloud-stuff piling up in the sky. He suddenly blinked at that. "Hello! How long did I sleep, Barnes?" Barnes told him. Hardwick shook his head to clear it.