"Black!" exclaimed the boys in a chorus. "Black as your shoe." "But--but I don't see how they--" Van stopped, bewildered. "They bleach it by injecting fumes of sulphur gas into the tanks; lime is also used to--" "To clear it after the dirt has come to the top," put in the boys in a breath. "Exactly so," laughed Mr. Powers. "I observe you are now at the home plate." [Illustration: "THESE TANKS ARE CONNECTED"] "We saw it done at the sugar-cane refinery," explained Bob. "I see," nodded Mr. Powers. "Well, the principle of making beet-sugar is the same as cane-sugar. By the use of chemical solutions the juice is cleared until it is perfectly white." Bob nudged Van with his elbow and the lads smiled understandingly. There was no danger of their forgetting Mr. Hennessey and his secret chemical formula. "The remainder of the process is also similar to that used in refining cane-sugar. The syrup passes from tank to tank, constantly thickening, and the molasses is extracted in the same fashion by being thrown off in the centrifugal machines when the sugar crystallizes. Molasses is often boiled two and three times to make second and third grade molasses for the trade, and you must remember in this connection that the names _New Orleans_ and _Porto Rico_ do not necessarily indicate where the product was made, but rather its quality, these varieties being of the finest grade." Mr. Powers rose and drew out a cigar. "I think I'm quite a lecturer, don't you?" he said. "I imagine your father, Van, could have told you this story much better than I have if you could have captured him for two hours on a train when he had nothing else to do. As it is I have had to fill his place, and I want you to inform him with my compliments that I am surprised to discover how completely he has neglected his son's education." With a mischievous twinkle in his eye Mr. Powers passed into the smoking-car.