SULPHUR. —Extraction nr Steam. 923

for moving the grating, a'", and the cover, i.The six apparatuses at Latera are supplied by acylindrical boiler, fired with wood, 4 feet 5 inches(V35 metre) in diameter, and 43 feet 8 inches(13*80 metres) long.

From the above description the method of work-ing is easily understood. The cover, i, is lifted off,the grating, a'", brought into a horizontal position,and three waggons of ore are tipped into the appar-atus. The cover is then firmly bolted on. Whilstthis is being done above, the receiver, k, is broughtunder the apparatus, the joint made tight, and thecocks, r ?•', connected. Steam is now let in; it first ofall condenses on meeting with the cold damp ore,and the temperature of the ore gradually rises till atlast it reaches that of the steam (125° to 135° 0., or257° to 293° Fahr.); the condensed water is run outof the receiver, and soon the sulphur melts andruns out of the ore.

After a lapse of thirty to fifty minutes the ore isdesulphurized, and the sulphur has collected in thereceiver. The steam is now shut off, and turned oninto an adjoining apparatus. On opening the cock,o', the sulphur runs out into a wooden mould stand-ing in the pit, z', and the operation is finished. Theconnection with the adjoining apparatus is broken,and any steam remaining allowed to escape. Thecover and the receiver are removed, and the screws,h, drawn back. The grating opens, and the desul-phurized ore falls down into the shaft and is usedin the mine for filling up the excavations.

The whole operation lasts from one and a half totwo hours; it does not do, however, to reckon uponmore than eight operations in the twenty-four hours.Eacli apparatus will take 53 cubic feet (1£ cubicmetre) of ore. The temperature required varieswith the ores, but 293 Fahr. (135° C.) is generallysufficient. The mine at Latera furnishes a verycompact ore, which is not thoroughly acted on bytins temperature. The average contents at Lateraamount to about 13 per cent.; the yield is 11-Jr toIlf, so that 1 j to 1£ per cent, of sulphur remains inthe residues. Each operation, with about 25 to 27-£cwts. (1300 to 1400 kilos.) of ore yields about 3Jcwts. (165 kilos.) of sulphur, and requires as fuel 2$cwts. (130 kilos.) of medium quality oak, with 10per cent, of water. The amount of fuel will varyvery little with the yield; it would be more, per-haps, in treating very compact ores.

In order to compare the steam and calcarone anddoppione processes exactly, we assume that it is thecase of a mine furnishing yearly 30,000 tons of orewith 20 per cent, real contents of sulphur, the cubicyard weighing 19J cwts. (1 cubic metre weighing1300 kilos.). In reality, it is only the steam appa-ratus and calcarone that come into competition,because the doppioni are only fit for a small output,require ore with very little or no moisture and muchfuel, and are soon worn out as the iron gets eatenaway.

A furnace with eight retorts, working 20 per cent,ore, yielding 17 per cent., can make two distillationsin twenty-four hours, working over 2400 kilos. (47

cwts.) of ore, and producing 408 kilos. (8 cwts.) ofsulphur. Omitting a sinking fund and general ex-penses, a ton of sulphur under these circumstanceswould cost:—■

Francs.

5,900 kilos. 20 per cent, ore, with 20 per cent.

yield, at 4 francs 60 cents. * per ton,.27*14

2,500 kilos, wood, at 15 francs per ton,_,.. 37*50

Wages,.18*75

83*39

This holds good for ores like those found atLatera. In the case of the more fusible ores inthe Romagna three distillations may be made inthe twenty-four hours, and the cost of fuel andwages becomes less, so that the cost price is reducedfrom 83 francs 39 cents, to 64 francs 63 cents.

A doppione furnace, with eight retorts and a shed,will cost from 3500 to 4000 francs.

Cost of 1 ton of sulphur by the calcarone process,excluding sinking fund and general expenses :—•

Francs.

7,140 kilos. 20 per cent, ore, yielding 14 per

cent, at 4 francs 60 cents.,.32*84

Filling, liquation, &c.,. 6*75

Superintendence, storing, &c.,. 1*35

40*94

Cost of 1 ton of sulphur, with the steam appa-ratus:—

Francs.

5.405 kilos, of 20 per cent, ore, yielding 18£

per cent., at 4 francs 60 cents, per ton,.... 24 *86

Filling, liquation, &c.,. 5*65

360 kilos, oak, with 10 per cent, moisture, or

160 kilos, coal at 65 francs per ton,.10*40

Superintendence, storing, sundries,. 2*50 *

43*41

It has been assumed that the eight apparatuseswill make 57 liquations in twenty-four hours, threecharges being put through every eight hours. Eachapparatus working through 1950 kilos, of ore as acharge would give 360 kilos, of sulphur; in twenty-four hours, therefore, 20,502 kilos, of sulphur wouldbe obtained, and the assumed annual out-put of30,000 tons would be worked through in 270 days.

Taking 100 francs as the value of the ton ofsulphur at the mine, we get for the calearoni—

Francs.

4200 tons, at 100 francs,. 420,000

Expenses, 4*200 X 40*94. 171,948

Profit,. 248,052

For the steam apparatuses—

Francs.

5500 tons, at 100 francs,. 550,000

Expenses, 5500 X 43*41,. 238,755

Profit,. 311,245

AA'e have therefore a sum of 63,193 francs in favourof the steam process. However, the original costand expense of repairs— i.e., the sinking fund—alterthis result considerably.

AYorking with calearoni on the scale above men-tioned would require at least 30 apparatuses, at

* Tliis is 50 centimes less than the sum mentioned bySignor Pakodi as the cost of the ton of ore on the mine.