1823.] Process of smelting Copper'. tl7 



and other volatile substances. The sulphur that is expelled is 

 in no part sublimed as flowers of sulphur, but is all acidified, 

 and the process being conducted with admission of atmospheric 

 air is properly a roasting. 



Process II.— The Melting of the Calcined Ore. 



The calcined ore is delivered, as in the raw state, to the work- 

 men in boxes containing 1 cwt. each. The charge is deposited 

 in the same manner in a bin placed on the top of the furnace, 

 and from thence passed into the interior as required. When the 

 charge is let down and spread over the bottom, the door of the 

 furnace is put up, and well luted. Some slags from the fusion of 

 the coarse metal or sulphuret are added, not only on account of 

 the copper they contain, but to assist the fusion of the ore, being 

 chiefly composed of oxide of iron. These are thrown into the 

 furnace through the front door. 



After the furnace is charged, the fire is made up, and the main 

 object of the smelter is to bring the substances into fusion : it is, 

 therefore, in this respect different from the calcining process. 

 When the ore is melted, the door of the furnace is taken down, 

 and the liquid mass well rabbled, or stirred, so as to allow of 

 the complete separation of the metallic particles from the 

 slags or earthy matters, and to get the charge clear of the 

 bottom of the furnace, which is made of sand, and soon becomes 

 impregnated with metal. The furnace being ready ; that is, the 

 substances being in perfect fusion, the smelter takes an iron 

 rabble, and skims off, through the front door, the sand or slags 

 consisting of the earthy matters contained in the ore, and any 

 metallic oxides that may have been formed, which, being speci- 

 fically lighter than the metals in the state of sulphuret, float on 

 the surface. When the metal in the furnace is freed from slags, 

 the smelter lets down a second charge of ore, and proceeds with 

 it in the same manner as with the first; and this he repeats until 

 the metal collected in the bottom of the furnace is as high as 

 the furnace will admit of without flowing out at the door, which 

 is usually after the third charge ; he then opens a hole, called the 

 tapping hole, in the side of the furnace, through which the metal 

 flows into an adjoining pit filled with water. It thus becomes 

 granulated, and collects in a pan at the bottom of the cistern, 

 which is raised by means of a crane. It is then filled into bar- 

 rows, and wheeled to the place appointed for its reception. 



The slags received into moulds made in sand in the front of the 

 furnace, are removed after each charge, and wheeled out of the work 

 to the slag bank, where they are broken, and carefully examined ; 

 any pieces found to contain particles of metal, are returned to the 

 smelter to be remelted; and unless the slag is very thick and 

 tenacious, the copper which they may contain is found at the 

 bottom. What is clean or free of metal is rejected. These 

 blags are composed of the earthy matters contained in the ore 



