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



be the ease. When the copper has attained its maximum tough- 

 ness and malleabiUty, it is laded into ingot moulds, and is known 

 as "tough pitch copper." If the poling process is continued 

 beyond a certain point, the metal loses much of its toughness 

 and malleabihty, and is known as " overpoled copper." 



Dry Copper. — Determination of the amount of suboxide. The 

 sample operated upon was made at the Hafod Works, Swansea, in 

 the year 1848, in the presence of Dr. Percy. 



(a). By heating a knmvn weight of dry copper in hydrogen and 

 weighing the ivater produced. — Some of the metal cut from the 

 ingot was rolled out as fine as possible and cut into small pieces, 

 of which 132"34 grs. were placed in a German glass tube, Avhich 

 was connected with a weighed tube containing chloride of cal- 

 cium. A current of dry hydrogen was then passed through the 

 tubes, and, after complete expulsion of the air, heat was applied 

 to that containing the copper. When the temperature rose to 

 redness, a distinct odour of sulphm-etted hydrogen was perceived 

 in the escaping gas, which (dnstantly blackened lead paper. 

 This production of sulphuretted hydrogen is curious, because it 

 shows that the copp^f \satuf ated with suboxide still retains a 

 trace of sulphur in some form or other. During the progress 

 of the experiment, a slight metallic sublimate was formed in the 

 cooler part of the tube — but in a part much too hot for arsenic 

 to condense,— which was found to contain lead. The quantity 

 was, however, too small for any very exact experiments to be 

 made upon it. After continuing the experiment for some time, 

 the tube containing chloride of calcium was disconnected, and 

 when cold reweighed. The weight of water was 1'93 gr., which 

 is equivalent to 102 1 per cent, of suboxide in the dry copper. 

 In another experiment, 136'41 grs. of the same dry copper gave 

 1*82 gr. of water, which is equivalent to 9"34 per cent, of sub- 

 oxide. Sulphiiretted hydrogen was again observed at the begin- 

 ning of ihe experiment. It is certain that the hydrogen em- 

 ployed was free from sulphuretted hydrogen and also from water. 

 The difference in the results shows that the method cannot be 

 relied on for accuracy. 



{b). By melting a known weight of dry coppei' in hydrogen and 

 estimating the oxygen by loss. — The apparatus employed was a 

 small Stourbridge clay crucible fitted with a perforated lid. It 

 was filled with hydrogen by means of a small porcelain tube 

 which passed through the perforation in its lid, and was heated 

 by charcoal arranged in a convenient furnace. Satisfactory 

 results were not obtained ; because, when the dry copper was 

 melted in this waj'^, it was found that great spirting occurred, 

 and that the projected globules could not be all collected from 



