51 



working is a tedious and rather laborious process, but a description of the manner 

 of doing it will properly come within my account of the Cornwall and Devon- 

 shire mines. It is a great economy to have the ores submitted to this preliminary 

 operation before shipment, as it induces, among other advantages, a very consid- 

 erable saving in freight ; and is, in fact, absolutely essentia! to the successful ■ 

 working of the poorer ores. 



The ore, having been pulverised, is carried by railway and steam power up to 

 the Hoppers, from whence it is passed into the furnaces, (below the Hoppers,) 

 and there subjected to a high degree of heat, for twelve hours, by which time it is 

 well calcined. This drives ofT much of the arsenic and sulphur with which it is 

 combined. It is then carried to another furnace, where it is melted. The slag is 

 lighter, floats on top, and i$ the first drawn off. Fluxes are seldom necessary, 

 and never so, except with a very refractory ore, when fluale of lime is used for that 

 purpose. The first slag, which is usually remelted, generally acts as a sufficient 

 flux of itself. It is often seen crystallized in various forms, exhibiting a beautiful 

 pavonine play of colors. The crude copper is now broken up aryl remelted, with 

 a current of air passing through it for the purpose of o.xidising the iron with 

 which it is mixed, and is then drawn off, into a tank of cold water, to granul.ite. 

 The water is prevented from becoming hot by a cold stream continually running 

 through the tank. The object of the granulation is to separate the metal into 

 small globules, so that the fire may circulate freely through and amongst it, when 

 again subjected to its purifying action. After granulation it is again roasted or 

 calcined for thirty hours, and is then removed to another furnace, when it is 

 mehed, with a draft of air passing through it, as before, to effect a still further 

 oxidation of the iron; from this furnace it is drawn off and run into pigs. It is 

 then again broken up, remelted, and, in a fluid state, conducted into a refinery, 

 among burning charcoal, from whence it is run into ingots, or into plates about 

 18 inches square by two or three inches thick. This is sometimes the copper of 

 commerce; but it is usually rendered malleable and ductile by the following pro- 

 cesses, viz: it is clipped, heated, and rolled, and cut into sheets, Say two feet 

 long ; again heated and rolled ; then again heated, doubled, and rolled, and some- 

 times (depending on its quality) again rolled, without additional heating. 



This is called finishing : it is then immersed in a bath of uric acid for the 

 purpose of brightening the metal, and removing the appearance of impurities from 

 the surface. It is then put into a furnace ; then immersed in cold water, from 

 which it is brought out bright. It is then taken to a machine, where its four 

 edges are clipped smooth, leaving it about three feet long and one wide, in thin 

 sheets. It is then assorted, weighed, and stamped with the weight per square 

 foot, which ranges from 10 to 20 ounces. 



In some of the establishment?, the processes are more simple ; but I should 

 doubt these being so efficient. As, for instance, the metal is granulated from the 

 first melting, direct, and after the second melting it is not broken up, but remelt> 

 ed in mass ; and, in rendering it malleable, it is not always submitted to so many 

 heatings and rollings. At Mr. 'W'illiams'n works, an engine of 96 horse powe 



