82 Mr. D. Mushet on the Alloys of Iron ajid Copper. 



racy in defining the nature and quality of the iron which has 

 been the subject of the union. Most of the books entirely over- 

 look the various states of iron, and fail to distinguish whether 

 the subject-matter of the experiment was cast iron, or steel, 

 or iron in a state of malleability. The same remark applies to 

 the experiments of Mr. P. N. Johnson as above, who, though he 

 states that he effected an union between iron and copper, yet 

 leaves it doubtful whether the iron was not steel or cast iron 

 instead of pure or malleable iron. The well-known affinity 

 of iron for carbon precludes the possibility of malleable iron 

 being heated and melted in contact with a large dose of char- 

 coal (as was the case in his experiments,) without its passing 

 into the state of steel or cast iron. So that the experiments 

 of Mr. Johnson may be considered as representing, not the 

 union of copper with wrought or malleable iron, but with cast 

 steel or crude iron. Whether or not these were examples of 

 a real chemical alloy, or of a mere mechanical mixture, maybe 

 gathered from the following remarks, which are grounded on 

 an extensive series of experiments. 



It had for many years appeared a desideratum to me to 

 form castings for shafts, cranks, levers, beams, &c., of a sub- 

 stance that should possess the stiffness of cast together with 

 the power of tension and strength of wrought iron. It oc- 

 curred to me that such a discovery would enable the engineer 

 to construct more complete and convenient forms (particularly 

 in the machinery belonging to steam-boats and locomotive 

 engines,) than he is at present able to obtain from the cum- 

 brous forging, turning, and fitting of malleable iron. Such 

 an union of strength I naturally sought for in a mixture of iron 

 and copper ; and knowing that the copper ores of this country 

 are principally sulphurets of iron and copper, I commenced 

 my experiments by attempting the joint reduction of the iron 

 and copper. After many failures I so far succeeded as to effect 

 a perfect reduction into malleable matter of the whole contents 

 of any given sulphuret. But upon examining the results, it 

 was found that a very great uncertainty prevailed as to their 

 strength and quality ; and I soon ascertained that I had only 

 succeeded in obtaining a perfect separation from the ore, of 

 the united products of iron and copper. These masses of 

 alloy were arranged and classified as follows : 



1st. Ingots of a coppery coloured surface, covered with aii 

 exterior blackish shale in cooling resembling iron ; breaking 

 with a pale uniform homogeneous fracture, and producing an 

 action more or less on the magnetic needle. 



2ndly. Ingots with a gray coppery surface, covered also 

 with an exterior blackish shale in cooling resembling iron, 

 the under surface of a deep red coppery colour. Fracture 



