412 Mr. A. Dick's Contiibutions to the Metallurgy of Copper. 



were similarly altered ; and tliat this was not due to carbon ab- 

 sorbed by the metal and acting injuriously upon its malleability, 

 will be shown fully further on ; but it may be here stated, that 

 electrotype copper, which is nearly chemically pure copper — at 

 least that operated upon was, — remained perfectly malleable 

 after havingbeen melted under charcoal*. The charcoal employed 

 in these and all following experiments had been digested in hy- 

 drochloric acid and thoroughly washed with water, to get rid as 

 much as possible of the action of the ash upon the metal in pre- 

 sence of carbon. 



Demonstration of the presence of suboxide in tough pitch copper. 



{a). By heating a knoivn loeight in hydrogen and weighing the 

 tvater p7'oduced. — The metal was heated to redness in hydrogen, 

 when water was found to be produced. Experiments were then 

 made to determine the proportion of suboxide in the same way 

 as already described («) in respect to dry copper, and the results 

 obtained were equally discordant and unsatisfactory. Towards 

 the beginning of each experiment a trace of sulphuretted hydrogen 

 was produced, just as when dry copper was similarly operated on; 

 and it was ascertained that tough pitch copper does contain a 

 trace of sulphur, by dissolving it in nitric acid and testing the 

 solution for sulphuric acid. A small metallic sublimate contain- 

 ing lead was formed, as when dry copper was experimented on. 

 The highest amount of suboxide shown by this method was 2*95 

 per cent. 



When copper wire or foil was so treated, it was found to un- 

 dergo a curious change. After having been heated in hydrogen, 

 it could not be bent without at once breaking, and it lost its 

 lustrous surface. The pliability of the wire or foil could not be 

 restored by annealing it at a red heat in steam, which was em- 

 ployed because it exerts neither an oxidizing nor a reducing 

 action. The same loss of pliability took place when carbonic 

 oxide or coal-gas was employed instead of hydrogen. It evidently 

 arises from the porosity produced by the reduction of the sub- 

 oxide which the metal contains, and must be distinguished from 

 the brittleness produced by melting the wire or foil in any of 

 these gases. For if the metal be tirst melted in any of them 

 and then rolled out, which can be done though the metal cracks 

 slightly at the edges, it will be found that the foil so produced 

 is not in the least affected by heating in them ; moi-eover, elec- 

 trotype copper, which contains no suboxide, is not altered by 

 heating in any of them. 



{b). By melting a knoivn weight of copper wire in hydrogen and 

 estimating the oxygen by loss. — The same spirting took place as 



* The copper employed was prepared by Messrs. Elkington and Co., 

 Binniugbain. 



