"Out of coal? How funny! I wish I could see all about it," said Philip, looking more interested. "And so do I wish I could," added Kitty. "I don't see why it cannot be done," said papa. "If you really care to see it, and won't mind a few bad smells, I will ask Mr. Carter to-morrow morning, when he can take you around and explain things." The next day when Mr. Carter was asked about it, he said, "O, come in any day you like. About three in the afternoon would be a good time, because we are always newly-filling the retorts then." This sounded very nice and imposing to the children, and at three the next afternoon they started out with papa. The gas-house certainly did smell very badly as they drew near it, and dainty Kitty sniffed in considerable disgust. Philip suggested that perhaps she had better not go in after all; he didn't believe girls ever did go into such places. And upon that Kitty valiantly declared she did not mind it a bit, and sternly set her face straight. [Illustration: A RETORT.] Mr. Carter met them at the door. "You are just in time to see the retorts opened," said he, and led the way directly into a large and very dingy room, along one side of which was built out a sort of huge iron cupboard with several little iron doors. The upper ones were closed tight, but some of the lower ones were open a crack, and a very bright fire could be seen inside. Everything around was dirty and gloomy, and these gleams of fire from the little iron doors made the place look weird and ghostly. Long iron pipes reached from each of the upper doors up to one very large horizontal pipe or cylinder near the ceiling overhead. This cylinder ran the whole length of the room, and, at its farther end, joined another iron pipe which passed through the wall. "Those are the furnace-doors down below," said Mr. Carter to the children. "What you see burning inside of them is coke. Coke is what is left of the coal after we have taken the gas and tar out of it. The upper doors open into the retorts, or ovens, that we fill every five hours with the coal from which we want to get gas. Each retort holds about two hundred pounds, and from that amount we get a thousand cubic feet of gas." "Is it just common coal;" asked Kitty, "like what people burn in stoves?" "Not exactly. It is a softer kind, containing more of a substance called hydrogen than the sorts that are generally used for fuel. Several different varieties are used: 'cherry,' 'cannel,' 'splint,' and so on, and they come from mines in different parts of England and Scotland, chiefly. Glasgow, Coventry and Newcastle send us a great deal." Philip started as if a bright idea had struck him. "Is that what people mean when you're doing something there's no need of, and they say 'you're carrying coals to Newcastle?'"