326 Mr. Miishet o?i the Fusion and Appearance of Copper. 



but the quantity or depth of grain was nowise altered, al- 

 though the metal cut softer, and was covered with a thin crust 

 of shining oxide. From these details it may be presumed 

 that cementation opens the grain, renders the bar less dense, 

 but does not change the peculiar form of the arrangement. In 

 each case the copper after cementation was softer, a change 

 which seems favourable to rolling cold. The impure or rough 

 copper appears to be alloyed with another metal (no doubt 

 tin), which prevents that oxidation which pure copper in the 

 same circumstances would undergo. 



Besides the above, several bars were made from the rough 

 copper by a slower fusion, and with a longer exposure to the 

 charcoal ; and it was observable that the longer the exposure, 

 and the slower the fusion, the more yellow and refined was 

 the copper in the bar. 



Some of the bars produced in the course of these experi- 

 ments were attempted to be rolled ; but the success was va- 

 rious. Of those made from the pure copper, some rolled better 

 and others worse than any made from the rough copper : one 

 or two bars of the latter were equally malleable with the 

 former; but none rolled well either hot or cold. In those 

 bars in which the striated arrangement was most perfect, the 

 capacity for rolling was least, and those in which the minute 

 granular fracture prevailed, generally rolled the best. It cer- 

 tainly does appear that this tendency to crystallize, so de- 

 structive to malleability, is peculiar to English copper made 

 from the crucible. There are occasions, no doubt, when, the 

 proper temperature being hit upon, the bar would roll ; but 

 these occasions are so rare and uncertain that English copper 

 made in this manner could not be relied upon in the manipu- 

 lations connected with manufactures. There is no question that 

 the arts in this country suffer from the peculiarity of English 

 copper. For in consequence of it the malleabilization of that 

 metai is necessarily confined to the original process of refining 

 practised on the great scale by the copper smelters. It is very 

 different with Swedish and Russian copper, which I have seen 

 melted in considerable quantities in large crucibles, cast into 

 cakes or thick sheets, and afterwards rolled into boiler plate 

 and thin sheet copper. This subject requires and deserves a 

 scrutinous examination, with a view to discover the cause of 

 the uniform tendency of English copper to crystallize ; and 

 that cause may, perhaps, be found in the process employed 

 in this country for the smelting of copper ores, a process 

 which, however oeconomical and well calculated to overcome 

 quantity, has never yet produced pure copper. 



Should these remarks obtain a place in your Magazine, 



