Mr. D. Mushet 07i the Alloys of Iron and Copper. 83. 



specular, and beginning to exhibit distinct grains of copper' 

 apart from the iron, as if this metal had been saturated with 

 copper. Small hard and bright iron points appeared under 

 the file. These ingots were obedient to the magnet. 



3rdly. Ingots with an iron-coloured surface, and coppery 

 tints displayed under a black thin shale. Hard, and filing to 

 a coppery colour, mixed with bright spots. Fracture specular, 

 exhibiting a mixture of iron and copper, in which the former 

 appeared to prevail. Powerfully acted on by the magnet. 

 The lower surface cellular and crystallized, resembling pro- 

 ducts of fused steel. 



Though I have divided these products into three classes 

 only, yet I obtained many intermediate results, the iron present 

 in which I estimated at from 5 to 70 per cent, of the weight 

 of the copper. Beyond 5 or 7 per cent, of iron, no chemical 

 union took place ; and as the quantity of iron revived, was in 

 proportion to the charcoal added, so in the same proportion did 

 the separation of the two metals from each other take place. 

 From this it was inferred that malleable iron [i,e, iron contain- 

 ing the least possible quantity of charcoal,) would unite and 

 form a proper alloy with copper, but that steel or cast iron 

 would not do so. To try the validity of this reasoning, a new 

 series of experiments was instituted, having for their object the 

 direct union of a portion of copper with iron in the various 

 states of cast iron, steel, and malleable iron, the general re- 

 sults of which I will state as briefly as possible, without go- 

 ing into a detail of the various experiments. 



Pure malleable iron may be united with copper in any pro- 

 portion, until it equals, or even exceeds, the weight of the cop- 

 per ; the intensity of the copper colour increases, till the quan- 

 tities are equal ; and the fracture then becomes paler, in propor- 

 tion as the quantity of iron exceeds that of the copper. With 

 50 per cent, of iron the alloy possesses great strength : its hard- 

 ness increases with the quantity of iron, but its strength after- 

 wards decreases, and in cutting, it opens before the chisel. 

 The loss of strength in proportion as iron is added, arises, 

 I imagine, from the fibre of the copper being injured by the 

 very high temperature required to fuse the increased quantity 

 of malleable iron. The fracture of the ingots thus obtained is 

 always specular, with a glance arrangement, which betokens 

 a tendency to brittleness. 



If steel is fused with copper in the proportion of ^^^th of the 

 latter to ^gths of the former, an ingot resembling, and crystal- 

 lized like cast steel, will be obtained, but useless for forge 

 purposes, and incapable of receiving an edge. Not the slightest 

 symptom of coj)per, either on the surface or in the fracture, 



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