At the Gun Factory of Oberndorf, in Wirtemberg, peat is charred in the kiln represented in the accompanying figure. The chamber is 9 feet high, and 5-1/2 feet in diameter. The oven proper, _b b_, is surrounded by a mantle of brick _a a_, and the space between, _c c_, is filled with sand. Each wall, as well as the space, is 15 inches in thickness, and the walls are connected by stones _d d_, at intervals of three feet. Above the sole of the kiln, are three series of air holes, made by imbedding old gun barrels in the walls. The door, which serves to empty the kiln, is a plate of cast iron, the sides of its frame are wider than the thickness of the wall, and by means of a board _e_, a box _m_ can be made in front of the door, which is filled with sand to prevent access of air. The peat is filled in through _i_, a channel being arranged across the bottom of the kiln, from the door _f_, for kindling. When the firing begins, the lowest air-holes and _i_ are open. When, through the lower gun barrels, the peat is seen to be ignited, these are corked, and those above are opened. When the smoke ceases to escape above, all the openings are closed, _m_, is filled with sand, _i_ is covered over with it, and the whole is left to cool. It requires about 8 to 9 days to finish the charring of a charge. Several kilns are kept in operation, so that the work proceeds uninterruptedly. [Illustration: Fig. 23.--OBERNDORFER PEAT CHARRING KILN.] [Illustration: Fig. 24.--WEBER'S CHARRING FURNACE.--TRANSVERSE SECTION.] [Illustration: Fig. 25.--WEBER'S CHARRING FURNACE.--LONGITUDINAL SECTION.]