420 Mr. A. Dick's Contributions to the Metallurgy of Copper. 



The residue upon the platinum foil was found to weigh 0'003 gr. 

 It had a light reddish colour^ and dissolved almost entirely in 

 hydrochloric acid, the insoluble portion being probably a trace 

 of silica which had occurred in the copperas silicon derived from 

 the charcoal, which, although washed with hydrochloric acid and 

 water, was yet not chemically i)ure. The solution contained a 

 trace of iron, and did not give a blue colour with ammonia; but 

 owing to the extremely small amount of it, nothing further could 

 be detected. The only weak ])oint in the otherwise conclusive 

 nature of this experiment, is that the precipitate which formed in 

 the solution of baryta might have been sulphite, and not carbon- 

 ate of baryta ; and this gains strength from the fact, that a slight 

 sublimate having the colour of sulphur was observed at the be- 

 ginning of the experiment. The copper which had been em- 

 ployed in the previous experiment was therefore examined for 

 sulphur by dissolving it in nitro-hydrochloric acid, and after- 

 wards boiling the solution with excess of hydrochloric acid so as 

 to expel all nitric acid. The sulphuric acid in the solution was 

 then precipitated, and weighed as sulphate of baryta. It was 

 found that the copper contained 0"05 per cent, of sulphur. The 

 very similar reaction which sulphur and carbon would have given 

 in the preceding experiment was overlooked at the time, so that 

 it is still an undecided question whether copper takes up any 

 carbon by being melted under charcoal. This the writer hopes 

 to settle soon, and will give the results in another communica- 

 tion. The sulphur which the copper contained might have been 

 derived from one of three sources, but it is not certain from 

 which, viz. from the charcoal employed, the atmosphere of the 

 furnace, or from a little of the liquid from which the copper was 

 precipitated by the battery still remaining in its pores. The 

 charcoal had been boiled in hydrochloric acid and washed with 

 water, and should therefore have contained no sulphur compounds 

 likely to exist in charcoal ; but still, as a large quantity was em- 

 ployed to keep the metal whilst melting from running together, 

 it is possible that the small, though important, quantity of sul- 

 phur above mentioned may have been derived from this source. 



Changes produced in the appearance and properties of copper ivhich 

 has been incited and cast in different waijs. 



When electrotype copper is melted and cooled in hydrogen, it 

 may be hammered out without cracking, either when hot or cold. 

 It is equally malleable after having been melted in charcoal, 

 plate-glass, or common salt. 



When melted under charcoal and allowed to cool in the cru- 

 cible, the surface of the piece of metal is always found to be 

 covered with crystalline markings, especially its upper surface. 



