330 TJie Philosophical Society of Glasgow. 



be quite fine. After the heat is well up, the door is taken down, and 

 the slags, if any, skimmed off. An assay is taken out and tested by 

 hammering, so as to ascertain whether it is in a fit state for the 

 toughening operation. At this time the fracture is, in all probability, 

 crystalline, the colour deep red, and judgment is necessary to ascertain 

 what amount of carbon is necessary to bring it to the proper pitch, or, 

 in other words, fit for practical purposes. 



The first step towards toughening is covering the whole mass with 

 charcoal. A pole or young tree, generally birch, is then introduced 

 and held down in the melted metal, causing considerable ebullition and 

 escape of gaseous matter. This is continued, and more charcoal added, 

 till the refiner, by his assays often repeated, perceives the grain to have 

 become fine, close, silky, and light red. He tests its malleability and 

 toughness by beating it when hot on the anvil. If the bead of metal 

 does not crack he is satisfied, and proceeds to have it ladled out, the 

 ladles being covei-ed with clay. From them it is run into moulds of 

 the size required by the manufacturer. The usual capacity is twelve 

 inches wide by eighteen in length. 



I have not thought it necessary to enter into a description of the 

 various ores, either native or foreign, employed by the British smelter, 

 as I am anxious to give a short diagnostic review of all that has been 

 attempted since Mr. Vivian wrote, in 1823, to improve the process of 

 copper smelting, and render less expensive the production of a metal 

 so important in all our manufacturing interests. 



From the year 1823 till 1848 little or nothing was pubhshed descrip- 

 tive of copper silielting in England. In that year, however, M. Le 

 Play published a work, showing that, with one or two exceptions, the 

 operation was much the same all over Europe ; and that, in fact, simple 

 calcination and fusion was the only principle involved. So far he 

 brings the matter up in a more scientific manner, and selects his ores 

 with some reference to a definite chemical result. He insists much on 

 classification, and, with material of a certain per centage, does not 

 calcine, but fuses at once, and calcines the product, which of course is a 

 regulus or sulphuret. He also adds rich and pure ores in the formation 

 of his third metallic product, and the same in getting blistered metal 

 for his fourth product, previous to refining and toughening. This result 

 he does not gain without the addition of certain reducing agents, and, 

 as before stated, with only a certain class of ores ; but when treating 

 the ordinary ores of all per centages and qualities, he requires nine 

 operations — A, calcination of ores with pyritous gangue. 



j4— Melting of calcined ores, or with the poorest and most impure 

 rough ores, forming first metal. 



