494 



THE POPULAR SCIENCE MONTHLY. 



vided 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 con- 

 structed 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, h, c, d, 

 previously charged with the sulphur mineral. When the suljDhur has 

 been completely dissolved, the solution is run into the tank, y, 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 appa- 

 ratus (Fig. 6) generally consists of two cast-iron cylinders, c, measur- 



Fig. 6. 



''^SNIf®^^" 



ing 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 



