PYRITES 675 



Production of Iron PyrUcs in the United Kingdom in 1872 and 1873. 



sulphur, and the nature of the earth ; the calcareous pyrites are those in which it is 

 most easily formed, and they effloresce the soonest. Good pyrites, properly treated, 

 yield about two-thirds of their weight of vitriol.' See STJLPHUEIC ACID. 



In the chemical works of Yorkshire the ' coal brasses ' are exposed in thin beds, 

 which are often turned over to the action of the air. The sulphur is converted by 

 the oxygen of the air into sulphuric acid, which combines with the iron, forming 

 sulphate of protoxide of iron or copperas, which is dissolved out and crystallised. 

 The same result may be obtained more quickly by roasting the sulphur ores. 



Boasting of Pyrites. Figs. 1694, 1695 represent a furnace which has been long 

 employed at Fahlun in Sweden, and several other parts of that kingdom, for roasting 

 iron pyrites in order to obtain sulphur. This apparatus was constructed by the cele- 

 brated Gahn. Fig. 1694 is a vertical section, in the line Jed no of Jiff. 1695, which is 

 a plan of the furnace ; the top being supposed to be taken off. In both figures the 

 conduit may be imagined to be broken off at e ; its entire length in a straight line is 

 43 feet beyond the dotted line e n, before the bend, which is an extension of this 

 conduit. Upon the slope a b of a hillock a be, lumps, r, of iron pyrites are piled upon 

 the pieces of wood i, for roasting. A conduit, dfe, forms the continuation of the 

 space denoted by r, which is covered by stone slabs so far as /, and from this point 

 to the chamber, h, it is constructed in boards. At the beginning of this conduit there 

 is a recipient, g. The chamber h is divided into five chambers by horizontal parti- 

 tions, which permit the circulation of the vapours from one compartment to another. 

 The ores r, being distributed upon the billets of wood ii, whenever these are fairly 

 kindled, they are covered with 

 small ore, and then with rammed 1594. 



earth, 1 1. Towards the point m, 

 for the space of a foot square, the 

 ores are covered with moveable 

 stone slabs, by means of which 

 the fire may be regulated, by the 

 displacement of one or more, as 

 may be deemed necessary. The 

 liquid sulphur runs into the re- 

 cipient g, whence it is laded out 

 from time to time. The sublimed 

 sulphur passes into the conduit 

 fe, and the chamber ft, from which it is taken out, and washed with water, to free 

 it from sulphuric acid, with which it is somewhat impregnated; it is afterwards 

 distilled in cast-iron retorts. The residuum of the pyrites is turned to account in 

 Sweden for the preparation of a common red colour, much used as a pigment for 

 wooden buildings. 



Enormous quantities of iron pyrites exist in Spain, and are now being brought to 

 this country. The sulphur ores contain a small quantity of copper, which increases 

 their value. 



In the year 1838 the King of Naples granted a monopoly of Sicilian sulphur to 

 Messrs. Faix & Co. of Marseilles ; this had the effect of greatly increasing the price of 

 that substance, and the immediate result was the employment of iron pyrites as a 

 source of sulphur in the manufacture of sulphuric acid. The consumption of this 



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