108 On the Union of Copper with Iron, &c. 



by many writers on metallurgy to be cajDable of uniting in an 

 INDIRECT way, is yet by most operative men, as casters ot cop- 

 per, and otbers, positively denied to have any such capacity. 



I have had my attention directed to this subject, by being 

 summoned as an evidence in a cause Smith v. Frost. Mr. 

 Smith, who uses copper pans to boil trie ingredients for making 

 rt green pigment for painting and dyeing, had l)een recommended 

 to make use of cast pans, to save the expense of wrouglit ones ; but 

 these not answering his purpose, he employed me to ins})ect and 

 give my opinion on them. In my experiments I proved the 

 presence of tin and iron; the latter was in a very minute quan- 

 tity: but from the proportion of the former the contract was 

 supposed to be void. The opposite party however, being cop- 

 per-smiths or casters, positively asserted the impossibility of 

 the union of copper and iron. And finding, on incjuiring of se- 

 veral persons in the same way of business, that a similar opinion 

 generally prevailed, I resolved on making some experiments to 

 prove how far it was possible to unite these metals. 



I first mixed 100 parts of copper with two of iron, covering 

 them with rosin and filling the crucible v;ith pon-dered charcoal. 

 After being exposed to abrait 90' of Wedgwood's thermometer 

 for a quarter of an hour, the mixture gave a clean lump of copper 

 not quite so malleable as when unadulterated, and with a redder 

 grain. I then endeavoured to ascertain how nmch iron tlie cop- 

 per would take up, by covering 400 grains of pure copper with 

 iron filings, and filling the crucible as before. The produce was 

 8S0 grains, of a large red grain, bubbled in the inside as if occa- 

 sioned bv confined air, with a clean uneven surface, and possess- 

 ing nearly the malleability of zinc. 



^riie next thing was to prove the existence of the iron by the 

 usual process of analysis. The increased weight, indeed, clearly 

 proved its presence ; but I tho\ight the analysis necessary, to 

 prove that only the iron had entered into the composition. As 

 the iron I had used for the foregoing exjjeriments was slightly 

 oxidated, I fancied this might have facilitated the union. ! 

 therefore subjected 400 gr;uns of copper covered with black 

 oxide of iron (the crucible filled with charcoal) to a strong de- 

 gree of heat for half an hour. The produce was 52(i grains of 

 copper remarkably red, which on analysis nearly answered to 

 the increased weight as metallic iron. I con-^idcr the iron to 

 have been the cause of the copper having such a red appearance, 

 from its partially oxidating it : it may perhaps, too, have had 

 the effect of making it more brittle, by separating the particles 

 of metallic copper. I further ascertained that this oxidation 

 greatly facilitated the combination. Having melted 400 grains 

 of pure copper, with a clean bit of thick iron wire, taking care 



to 



