of refilled and unrejined Copper. 325 



on a creamy appearance. When cold, the surface of the ingot 

 thus obtained was less coppery-metallic than the surface of 

 the ingot in the first experiment, where charcoal was used, 

 from which it may be inferred that, owing to the absence of 

 charcoal, a certain degree of refinement had taken place. The 

 fracture possessed more of the red grain of good copper; the 

 strijje were less distinct and less crystalline; and the surface 

 instead of being convex, as in the first experiment, was con- 

 cave. 



Exp. No. 3. Some of the pure shotted copper was fused in 

 a black-lead crucible with an equal bulk of charcoal, and the 

 resulting ingot presented a more clean and perfect mass of 

 copper than the ingots obtained in Experiments No. 1 and 

 No. 2. The fracture presented a series of brilliant striae ar- 

 ranged from surface to surface, breaking off easily in the di- 

 rection of the perpendicular fibre ; a structure which seems 

 wholly incompatible with extension and malleability. 



Exp, No. 4. Some of the same pure copper melted simi- 

 larly, but not poured into the mould until it had nearly lost its 

 fluidity, formed an ingot less striated or crystallized than any 

 of the former, with more of that minute deep orange-coloured 

 grain which is peculiar to pure and malleable copper. From 

 the results of this experiment, and of No. 2, it would seem 

 that when copper is poured into the mould at as low a tem- 

 perature as is consistent with perfect fluidity, the fracture is 

 less crystallized, and the colour approximates to that ruby 

 grain which indicates the malleable state of copper. 



Four bars, one from each of the foregoing experiments, 

 were imbedded in burnt lime, shut up from the access of air, 

 and exposed in crucibles to the same temperature. The pure 

 copper bars (Nos. 3. and 4.) were on the surface considerably 

 oxidated, but those made from the rough copper (Nos. 1. 

 and 2.) were entirely free from oxide; and from this it may 

 be inferred that the alloy (principally tin) which still remained 

 in the copper prevented waste or oxidation. The bar from 

 Experiment No. 1. was not cut, but that from Experiment 

 No. 2. retained about the same quantity of grained striae as 

 before the cementation ; though, compared with a fracture of 

 the same copper that had not been cemented, the grain was 

 redder, the colour more brilliant, and the metal more ductile. 

 The bar from Experiment No. 3. was covered with a thin 

 coating of crystallized oxide exceedingly soft; the stria? were 

 more enlarged and adhesive, so that the copper, in cutting, tore 

 out in flakes, which separately were soft and ductile. The bar 

 from No. 4. when examined and compared with an uncemented 

 one was more open in the grain, redder, and more brilliant ; 



