Page:Popular Science Monthly Volume 26.djvu/510

494 with a dome-shaped lid, having an inlet-pipe, n, and outlet-pipe, o; its capacity is three tons. The store-tank, g, measures ten feet in diameter, by seven feet deep, has a capacity of ten tons, and is constructed of half-inch wrought-iron plates. The worm, h, is a coil of two-inch pipe. The boiler, i, is of twenty horse-power nominal, and must be placed where it will be impossible for bisulphide vapors to find their way to the fire-hole. Force-pumps are required to pump the bisulphide from the store-tank, g, into the extracting-vats, a, b, c, d, previously charged with the sulphur mineral. When the sulphur has been completely dissolved, the solution is run into the tank, f, and thence pumped into the still, e, where, by the application of steam in the jacket, the bisulphide is evaporated, and passes into the store-tank, g, for future use, while the sulphur forms a deposit in the still, and is collected therefrom. When the extracting-pans have been emptied of solution, steam is let in so as to force any remaining bisulphide vapors into the worm for condensation and recovery, thus avoiding waste of bisulphide and consequent risk of fire and explosion by ignition of its dangerous vapors. The bisulphide is allowed to remain all night in contact with the charge. The diaphragm at the bottom of each extracting-vat may advantageously be covered with bagging-cloth to filter flocculent matters from the bisulphide.

For the preparation of "roll" and "flowers of" brimstone, the crude sulphur has to be again subjected to heat. The fusing apparatus (Fig. 6) generally consists of two cast-iron cylinders, c, measuring



three feet long, by one foot in diameter, closed at one end by a door, e, and prolonged into a tube at the other, which leads into a brick-work condensing chamber, d. The retort, heated by a fire made immediately beneath, is completely surrounded by flues traversed by the heated vapors, which latter, before escaping to the chimney, heat a little pot, a, placed above the retort, and in direct communication