Mr. A. Dick's Contributions to the Metallurgy of Copper. 419 



About 672 grs. of electrotype copper, which had been melted 

 under charcoal, were mixed in the state of filings with recently 

 ignited chromate of lead, and the mixture was heated in a com- 

 bustion tube connected with a weighed set of Liebig's potash 

 bulbs, and a combustion was made as in the case of an organic 

 body. No gas was perceived to bubble through the potash solu- 

 tion. At the end of the experiment some air was drawn through 

 the apparatus, and the potash bulbs were reweighed. They had 

 increased only 0"115 gr. Assuming this to be carbonic acid, it 

 corresponds to 0"031 gr. of carbon in 673 grs. of copper. This 

 experiment is also inconclusive. 



A piece of the sheet made from the ingot which had been 

 rolled out by Mr. Forbes was cleaned by boiling in caustic pot- 

 ash. It weighed 221 '10 grs. It was laid in a platinum basin 

 which was immersed in a solution of sulphate of copper contain- 

 ing free sulphuric acid. The platinu.m basin was then con- 

 nected with the positive pole of a galvanic battery, and a plate 

 of copper connected with the negative pole was arranged over 

 the basin in the solution of sulphate of copper. The whole was 

 covered so as to exclude dust, and left till the residue of the 

 copper in the basin was very small. It still contained a little 

 metallic copper, which was removed by the action of a solution 

 of perchloride of iron containing some free hydrochloric acid. 

 The residue was then washed by decantatiou, dried, and weighed. 

 It had a very dark gray, or nearly black colour, and weighed 

 0"08 gr. When a portion of this was heated on platinum foil it 

 evolved a slight and peculiar odour, glowed for an instant, and 

 left a small incombustible residue. Another portion, weighing 

 0"012 gr., was placed on a veiy small piece of platinum foil, 

 which was introduced into a small glass tube, one end of which 

 dipped into a solution of caustic baryta protected from the action 

 of the air, and the other end of which was then connected with 

 an apparatus from vv'hich a very feeble current of air, perfectly 

 fi"ee from carbonic acid, could be sent. Some of this air was then 

 sent through the tube containing the slip of platinum and into 

 the solution of caustic baryta, and it was observed that no cloudi- 

 ness was produced in the liquid. The heat of a spirit-lamp was 

 then applied to that part of the tube where the piece of platinum 

 containing the po\i Jer was placed. At first a very slight subli- 

 mate was evolved, which had the colour of sulphur, and which 

 condensed in the cooler part of the tube. When the tempera- 

 ture of tiie platinum foil on which the powder rested had reached 

 redness, every bubble of air as it passed through the baryta water 

 produced a jirecipitate. After a short time the apparatus was 

 disconnected, and excess of hydrochloric acid was added to the 

 baryta solution, when the precipitate dissolved with effervescence. 



