122 Mr, Vivian's Account of the [Feb, 



mechanical, that of closing the grain, and altering the texture or 

 structure of the metal ? 



It is a remarkable circumstance that when copper is gone too 

 far, it oxidizes slowly on the surface, thus strengthening the 

 supposition of its being combined in that state with carbon, as 

 that substance, from its union with the oxygen of the air, would 

 prevent the oxidation of the metal. The surface of the liquid 

 metal in the furnace is also more than usually splendent when 

 over-poled, reflecting every brick in the roof, being then quite 

 free from oxide. 



Sometimes when copper is difficult to refine, a few pounds of 

 pig lead are added to the charges of copper. The lead acts as a 

 purifier, by assisting, on being oxidized itself, the oxidation of 

 the iron or any metal that may remain combined with the copper, 

 and not, as may be supposed, by uniting with the copper, and 

 thereby increasing its malleability. This is a mistaken notion, 

 and may lead to further embarrassment, as the smallest portion 

 of lead combined with copper renders the metal difficult to pickle, 

 or clean from oxide, when manufactured, as the scale or oxide 

 will not rise clean from the surface of the sheets. The lead should 

 be added immediately on the door being taken down preparatory 

 to skimming, and the copper should be well rabbled, and exposed 

 to the action of the air, so as to promote the entire oxidation of 

 the lead. 



Copper for brass making is granulated that its surface may be 

 increased, so as to combine more readily with the zinc, or cala- 

 mine. 



This is effected by pouring the metal from the ladles in which 

 it is taken out of the furnace into a large ladle pierced in the 

 bottom with holes, and supported over a cistern of water. The 

 water may be either hot or cold, according to the form to be given 

 to the metal. When warm, the copper assumes a round form, 

 and is called bean shot. When a constant supply of cold water 

 is kept up, the metal has a light ragged appearance, and is called 

 feathered shot. The former is the state in which it is prepared 

 for brass wire-making. 



Another form into which copper is cast, chiefly for exports to 

 the East Indies, is in pieces of the length of six inches, and 

 weighing about eight ounces each. These are called Japan 

 copper. The copper is dropped from the moulds immediately on 

 its becoming solid, into a cistern of cold water, and thus, by a slight 

 oxidation of the metal, the sticks of copper acquire a rich red 

 colour on the surface. 



The charge of copper in the refining furnaces at Hafod is 

 from three to five tons. The quantity of pure copper made 

 weekly in the Hafod works, is from 40 to 50 tons. In the 12 

 months ending June 30, 1822, the purchases of ore amounted to 

 24,400 tons, containing 2144 tons of pure copper. 

 Contiguous to the Hafod smelting work is a powerful rolling mill. 



