Mr. A. Dick's Contributions to the Metallurgy of Copper. 417 



of it was cast at Messrs. Robinson and Cotton's Works, Pimlico. 

 It was said to require a higher temperature for casting than 

 bronze. The surface of the casting was said to be good. No 

 experiments were made to ascertain how much siUcou copper 

 may be made to combine with in this way; but in one specimen 

 accidentally prepared, the quantity was very much larger than in 

 that alluded to previously. 



Effect of Carbon. — This has been supposed to be the cause of 

 the brittleness of overpoled copper. According to Karsten, 0'05 

 per cent, of carbon is sufficient to cause copper to crack when 

 hammered hot. He adds, moreover, that the presence of carbon 

 increases the influence of small quantities of lead, antimony, and 

 such metals as affect the malleability of copper. 



A great many experiments were made to ascertain the eff'ect 

 of carbon upon copper. It would be useless to describe all the 

 experiments which were made on this subject; accordingly those 

 only which seem most conclusive will be alluded to. It is of 

 course essential that both the copper and the carbon should be 

 as pure as possible. In examining the result of an experiment 

 made some years ago by Dr. Percy, the necessity of this was 

 brought prominently forward. A quantity of finely divided cop- 

 per (" best selected^" from Messrs. Newton, Keats and Co.) had 

 been diffused through charcoal powder, and heated strongly for 

 some hours for the purpose of ascertaining the effect of carbon 

 on copper. The shots of metal were afterwards melted together 

 under charcoal. It was found that the metal so treated could 

 be rolled into sheet or drawn into wire when cold, but that it 

 cracked when worked hot. On testing this copper, it was found 

 to contain a very notable quantity of silicon and a small quan- 

 tity of phosphorus and iron. These seem to have been derived 

 chiefly from the charcoal employed. 



It vvas found that small pieces of electrotype copper, after 

 having been melted under charcoal — which, as usual, had been 

 digested in hydrochloric acid and washed with water, — could be 

 hammered out without cracking, either when hot or cold. 



A mixture of rather large pieces of electrotype copper and 

 charcoal powder were heated together for about half an hour at 

 a temperature approaching whiteness. The contents of the cru- 

 cible were then stirred with a piece of wood, so as to cause the 

 metal to sink to the bottom of the pot, after which it was cast 

 into an iron ingot mould to be drawn into wire. The following 

 somewhat similar cx])criment was made at the same time. 



Several pieces of electrotype copper were placed in a crucible 

 lined with charcoal powder, which was then completely filled 

 with charcoal anfl exposed to a tem))erature apj)roaching white- 

 ness for about an hour. The furnace containing the crucible 



