“Well, slip that rope around his arms and legs while we do it,” said Phil, “or we’ll have trouble when he comes to.” This was a suggestion which they all recognized as altogether timely, and so the apparent corpse was carefully secured by two of the boys, while the rest worked at the task of restoring him to life. He “came to” in a little while, and lay stretched out upon the deck, weak and exhausted. Then, at Ed’s suggestion, the boys went below by the forward door, rolled away the obstructions, and threw open the door of the cabin, so that all the air possible might pass through it. It was half an hour at least before breathing became comfortable in that little box. Then Phil made a thorough exploration of Jim’s carpet-bag, bunk, and everything else that pertained to him. His only remark as to the result of his personal inquiry was:-- “I guess we needn’t trouble ourselves about having arrested this man.” While waiting for the air to render the cabin habitable again, Constant said, “But, Ed, how did he _drown_ without going into the water? I don’t understand.” “Neither do I,” said Will Moreraud; “but he was drowned all safe enough. I’ve seen too many drowned people not to know one when I see him.” Then Ed explained:-- “That cabin is a little box about ten feet by twelve, and six feet high, and when shut up it’s nearly air tight. It contains only a little over seven hundred cubic feet of air. These chemical fire extinguishers are filled with water saturated with soda or saleratus. There is a bottle in each one, filled with oil of vitriol, or a coarse, cheap sort of sulphuric acid. It is so arranged that when you turn the thing upside down the bottle breaks, and the acid is dumped into the water. Now when you pour sulphuric acid into a mixture of water and soda, the soda gives off an enormous quantity of what is commonly called carbonic acid gas, though I believe its right name is carbon dioxide. At any rate, it is the same gas that makes soda water ‘fizz.’ But when you turn one of these machines upside down you get about ten or twenty times as much of the gas in the water as there is in the same quantity of soda water; and when you turn this doubled and twisted soda water loose it gives off its gas in enormous quantities. Now this gas is heavier than air, so when it was set loose down in the cabin there, it sank to the bottom, and the air floated on top of it. As the cabin filled up with the gas the air came out through the hole in the scuttle and the cracks round it. Pouring that gas into the cabin was just like pouring water into a jug; the gas took the place of air just as the water in the jug takes the place of the air that was in it at first. “Suppose you let a lighted lantern down into the cabin, Will,” suggested the older boy, “and see what happens.” Will did so, and the lantern went out as promptly as it would have done if plunged into water.