in Muriatic Acid^ as a Test of its Dtirahility. 445 



thoroughly dried. The pure copper had lost at the rate of 5J 

 grains in 100. But the unrefined copper, on being weighed, 

 seemed to have gained half a grain ; so that either a mistake 

 must have been made in the weighing, or else a portion of 

 unexpelled moisture had remained in the porous flakes of 

 the copper. 



Six ounces of unrefined copper were mixed with three times 

 their bulk of charcoal, and exposed for six hours to a high 

 heat of cementation, much beyond what in the absence of 

 the cementation would have sufficed to melt the copper. 

 The flakes of copper were found surrounded by the charcoal, 

 welded together without fusion, and soft and extremely 

 flexible. Six ounces of the pure copper shots were treated in 

 a similar manner ; but the result was so far different that no 

 adhesion of the masses had taken place, and the only percep- 

 tible change was a slight cracking or bursting uj)on the sur- 

 face of the spheroids, which may be considered as a prelude 

 to fusion. Both results were melted down with charcoal and 

 run into iron moulds. The unrefined copper, when cold, was 

 the strongest and softest ; a bar of it, about f ths of an inch 

 thick, cut easily across with a knife, and in colour and general 

 appearance it very nearly resembled Swedish copper. Ano- 

 ther piece was flattened out thin when cold for the purpose of 

 immersion in the muriatic acid. The pure copper was melted 

 in rather a higher degree of heat, and although not teemed 

 until it had assumed a creamy surface, and the crucible had 

 fallen to a low red temperature, it was crystallized through- 

 out the whole fracture. The surface and the fracture of this 

 copper were of a red colour ; the body weak, and tearing with 

 facility into pieces. Fragments for immersion were cut off 

 and flattened. 



The following specimens were then placed separately in 

 muriatic acid. 

 - No. 1. Pure copper, cut off with a chisel, ... 53 grains. 



2. Ditto, flattened, ... 30 — 



3. Unrefined copper, cut off with a knife, 39^^ — 



4. Ditto, flattened, in which stuck ^\ aq 



minute portion of the knife J 



On the morning of the third day the following remarks were 

 made upon their respective solutions. 



No. 1, Light green colour, very transparent when dashed 

 against the sides of the glass. No. 2, Equally transparent, but 

 the green was brownish and not so decidedly cupreous. After 

 continuing the immersion for 48 hours longer, the acid was 

 poured off and the specimens were well washed and dried. 



