924 SULPHUR.— Fkom Pyrites.
1400 francs = 42,000 francs, which might be paidoff in eight years, with a yearly sinking fund of4398 francs.
Franca.
Eight apparatuses (40 tons each),. 50.000
Two steam boilers and chimney,. 28,000
Jacketing, pump, framework,. 4,000
Masonry, roofing, &c.,. 12,000
94,000
These figures are estimated according to the pricesof ironwork in Sicily in 1873, including carriageand duty.
The cost of the apparatuses should be paid off infive years, that of the boilers and sheds in ten years.This would require an annual sinking fund of 16,473francs; therefore the above-mentioned profit of63,193 francs would be reduced to 46,720 francs.The steam process therefore still effects a very con-siderable saving. The ores, too, can be worked overas fast as they are raised, and there is no necessity forstoring the ore for a considerable time, as is cus-tomary in Sicily . Finally, the workmen can easilybe paid according to the amount of sulphur pro-duced. The process is carried on in inclosures,and there is no fear of any sulphur being stolen.
The mode of leasing mines in Sicily preventsmany lessees from introducing these apparatuses.The mines are let out for a certain number of yearson condition of giving up 20 to 36 per cent, of theproduce in kind. Under these circumstances thesteam process would be particularly advantageousto the proprietor or “ lord ” of the mine, but not somuch so to the lessee.
If the rent were 30 per cent, of the out-put, theprofit of the lessee would only be increased 13,448francs, whilst the lessor or “lord” of the minewould get 1665 tons of sulphur instead of 1260tons, and would thereby gain 40,500 francs.
We have not taken into consideration any royaltyfor the use of the patent. It may now be seenwhat an error inventors made who only looked atthe higher yield, and not at the total cost of work-ing, and asked for a royalty of 4000 to 5000 francsfor each apparatus. With the expensive fuel inSicily and the Romagna, the steam process will onlybe possible where the patent royalties are verysmall, as at Latera, or where the patent rights havelapsed.
The steam apparatus now used at Castel Terminidiffers from that of Pirckiiey. It consists of acylindrical vessel of cast iron, about 16 feet long by4 feet in diameter, closed at one end. It is mountedlike a gun on trunnions. The cylinder is chargedwith the open end uppermost, the cover is thenfastened on, and the cylinder turned to a horizontalposition; steam is let in, and the liquation of thesulphur effected. The sulphur is run off by tiltingthe cylinder, and finally, the spent residues are dis-charged by removing the cover. The horizontalposition during fusion is found to be preferable, asthe melted sulphur has only to drain through a heightequal to the diameter; whilst, if it were maintained
in a vertical position, it would have four times thatdistance to drain, and the time for a fusion wouldbe considerably lengthened. There is a great lossof time in loading and unloading, and as comparedwith the calcaroni, a very small quantity of ore canbe treated at one time. Admitting all the defectsof the calcaroni, it is doubtful whether anything hasyet been invented to supersede them entirely, forthe cost of liquation is so small, only about 5 francsper cassa of 6-40 cubic metres (85 cubic yards).
8. Extraction of Sulphur by Bisulphide of Carbon .—The process proposed by Bollmann consists of threeoperations*—1st. Desulphurization of the ore bymeans of successive washings with bisulphide ofcarbon in a series of vessels communicating withone another. The ore and the solvent should passregularly from one vessel to another in the inversesense - , that is to say, the first vessel should containnearly exhausted ore and pure bisulphide of carbon,and the last bisulphide of carbon all but saturated, andfresh ore. 2nd. Distillation of the saturated solutionof sulphur in a retort heated gently. The sulphuris obtained as a residue, and the bisulphide of carboncondensed at the same time serves for another opera-tion. 3rd. Separation of the bisulphide of carbonmechanically mixed with the sulphur by means of ajet of superheated steam. The bisulphide is con-densed with the steam, and separates itself as alayer floating on the water. The process was triedin 1868, near Naples, but it has not been introducedat any sulphur mines; indeed, it is doubtful whetherit could be worked profitably on a large scale.Pelouze * proposes to dissolve out the sulphurfrom poor ores and Laming’s mixture by means ofcoal-tar oils.
Determination of Sulphur in SulphurousEarths. —A rough and ready method of determiningthe quantity of native sulphur is to weigh out aquantity of the ore and set fire to it. The loss ofweight by burning gives roughly the amount ofsulphur. A more exact method is to use bisul-phide of carbon to dissolve out the sulphur; infact, the method proposed for extracting sulphuron a large scale. According to Anthon, f “ 2 grams,of coarsely pulverized ore are heated in a glass tubeof 10 to 16 inches in length and 4 lines in width,which is closed on one side, and into the open endof which another tube, also closed on one side, isintroduced up to within 3 inches of the ore. Whenno more sulphur issues from the ore, that piece ofthe latter tube in which the sulphur has been con-densed is cut off and weighed. The sulphur is thenremoved, and the empty tube weighed again, thedifference of the two weights giving the availableamount of sulphur in the ore.” For treating largerquantities an earthen retort is used, and the sulphurthat distils over is collected and weighed.
Direct Extraction of Sulphur from IronPyrites and other Sulphides. —The immensequantity of sulphur stored up in the shape of
* Berg undHuttenmannische Zeitung,vo\. xxxi. p. 184.1872.
t Statistics of Mines and Mining, it. W. Itaymond, Wash-ington, 1873.