918

SULPHUR.— Extraction.

Sulphates of zinc, cobalt, iron, copper, and lead areminerals found in nature, and have no doubt allbeen produced by the oxidation of the sulphides ofthese metals.

In the vegetable kingdom some of the essentialoils—such as oil of mustard, oil of garlic, and oil ofassafcetida—contain sulphur.

Among the components of animal substancescontaining sulphur may be mentioned the proteoidsor albuminoids; the blackening of a silver spoon bya boiled egg is a familiar illustration of the fact.Fibrin , whether of blood or flesh, also containsmore than 1 per cent, of sulphur; and sulphurenters into the composition of casein, protein,lisematocrystallin, and globulin, as well as of hair,horn, nails, and feathers. Enough has thereforebeen said to prove that sulphur is a very widelydistributed element, in the animal, vegetable, ormineral kingdoms.

Uses of Sulphur. —Sulphur is used in making sul-phuric acid, sulphurous acid, and many of the com-pounds of sulphur, such as hyposulphite of soda,bisulphide of carbon, artificial vermilion, &c. It isone of the constituents of gunpowder, and is usedin the manufacture of lucifer matches. Large quan-tities of sulphur in powder are used in Italy, France ,and Spain , for sprinkling vines as a preservativeagainst the disease known as o'idium. Sulphur isused for hops in the same way. Some is used inmedicine, and it is finally employed as a cement, andfor taking casts of coins, medals, &c.

Direct Extraction of Sulphur from Sulphurous Earths.—This extraction may be performed in variousways:—

1. Melting in pans.

2. Liquation in iron cylinders.

3. Distillation in earthen pots.

4. Liquation in small kilns ( [calcarelle ).

5. Liquation in large kilns ( calcaroni).

6. Distillation in iron retorts ( doppioni ).

7. Liquation by means of steam.

8. Extraction by bisulphide of carbon.

9. Processes of IIirzel, Gill, and Kavser. *

1. Melting in Pans .—This method has been em-ployed for rich sulphur ore, and stuff that is in toofine a powder to be treated conveniently by liquationin kilns. The accompanying Fig. 5 f shows the kindof pan that was used at Lercara in Sicily . The orewas thrown into the pans little by little, and as itmelted, the workman drew out the earthy particleswhich settled at the bottom. A high heat is notadvantageous. This maybe inferred from what hasbeen said before respecting the changes which takeplace during the fusion of sulphur at differenttemperatures. For the purpose of purification thelowest heat consistent with perfect fusion had to beemployed. The liquid sulphur was thus in itsthinnest state, easily allowing the earthy particles tosubside. When the pan was full of melted sulphur

* Described by Parodi ; they are of no commercial im-portance, and need not be further noticed here.

t Copied from Paroih’s figure in his work, “Bull’ estrazionedello Sollo in Sicilia ” Florence, 1873.

the workman allowed it to settle a little, and thenladled out the sulphur into moulds. The two or

Fig. 5.

three last ladles were very impure, and had to betreated in the kilns together with the residues of theoperation, which still retained a considerable quantityof sulphur.

2. Liquation in Iron Cylinders .—This was a methodin use at one time in places in Sicily . The sulphurearth was heated by means of a wood fire in ironcylinders inclined towards the front. The cylinders,containing each some 4 tons of ore, were closedduring the operations, and there was thus little lossfrom sublimation or oxidation. However, much sul-phur remained in the residues, and the cast iron wasrapidly corroded. At Swoszowice, near Cracow , theprocess adopted is partly liquation, partly distillation.The ore is heated in cast-iron sloping tubes, each ofwhich holds rather more than 1 cwt. of mineral.Some sulphur is collected by tapping it off at thelower end of the tube, and the rest is obtained bythe condensation of the vapours that escape. Forfigures and description, see “Berg und Iliitten-miinnische Zeitung,” 1861, pp. 1-15, and “Metal-lurgy,” by Crookes and Roiirig, p. 710.

3. Distillation in Earthen Pots .—-This system,though never used in Sicily , has been employed inthe Romagna, and may still be seen at the Solfatara,near Naples, though the production is very smallindeed, a a are two earthen jars standing upon a

Fig. 6.

raised support of bricks. The mouths of these jarsprotrude slightly over the top of the furnace. Thisis for the purpose of allowing the operator to fillin the charge and remove the earthy residuum. Ahollow tube or arm projects laterally and slightlydownwards from each of the pots or retorts, whicharm is thrust into another pot or vessel to receivethe sublimed sulphur which condenses in it. Whenthe subliming pot has received its charge the lid