Mr. A. Dick's Contributions to the Metallurgy of Copper. 4ll 



the inside of the Hd and crucible for the purpose of being 

 weighed. This took place even wlien the heat was applied very 

 slowly, and was apparently due to the escape of the water formed 

 by the reduction of the suboxide. 



{c). As loss btj the wet rvay. — A weighed portion of dry copper 

 was dissolved in nitric acid, and the solution was saturated with 

 caustic potash and boiled. The precipitate was collected on a 

 filter, washed, ignited, and weighed. It was evaporated with 

 nitric acid until its weight was constant. From the oxide ob- 

 tained the metal was calculated, the difference between the weight 

 of which and that of the dry copper was estimated as oxygen. 

 This method will not yield absolutely accurate results, because 

 dry copper is not a mixture of chemically pure copper and sub- 

 oxide, but contains in addition small quantities of lead, antimony, 

 and other metals, which will interfere slightly with the result, 

 owing to the difference in their atomic weights : still the error 

 must be very small. In one experiment, 10' 73 grs. of dry cop- 

 per yielded 13-18 grs. of oxide ; in another, 9" 17 grs. of dry 

 copper yielded 11'26 grs. of oxide. From the first experiment, 

 the dry copper contained 98*09 per cent, of copper ; from the 

 second, it contained 98*01 per cent. The difference estimated 

 as oxygen corresponds to 17*04 per cent, of suboxide of copper 

 by the first experiment, and 17*74 per cent, by the second. 



Tough Pitch Copper. — In this condition, the metal, like che- 

 mically pure copper in certain states, is possessed of the highest 

 degree of malleability and ductility at all temperatures. It is 

 well known that tough pitch copper cannot be remelted, except 

 under special conditions, without losing in part its malleability. 

 Karsten showed that it contained suboxide of copper, and that 

 this was essential to counteract the injurious effect exerted upon 

 the malleability of the metal by foreign metals. Hence it is 

 easy to conceive why tough pitch copper can scarcely be remelted 

 without losing part of its malleability ; because, if the atmosphere 

 is a reducing one, the suboxide is reduced, and the metal assumes 

 the brittleness of overpoled copper ; or, if it is an oxidizing one, 

 too much suboxide is formed, and the metal assumes the brittle- 

 ness of dry copper. The following experiments were made upon 

 this subject. The tough pitch copper operated upon was either 

 an ingot made at the Hafod Works, Swansea, or else commercial 

 wire or sheet. 



Tough pitch copper from the ingot, after having been melted 

 in hydrogen, was so brittle that it split at once when hammered 

 at the ordinary temperatm*e, and the brittleness was much greater 

 when the metal was hot. Various samples of wire and sheet, 

 similarly treated, were all found more or less brittle, especially 

 when hammered hot. Similar samples melted under charcoal 



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