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VIII. — The Chemical Changes which Pig Iron undergoes 

 during its conversion into Wrought Iron. 



By F. Crack Calvert, F.C.S., M.R.A. Turin, and 

 Mr. Richard Johnson. 



[Read March 10th, 1857.] 



uing to make some improvements in the manufacture of 

 iron, we carefully examined the various analyses which had 

 been made of pig and wrought iron, and we found that 

 no comparison could be drawn between the results, as the 

 samples analysed had been obtained from different sources; 

 and also that no detailed analysis had been published of the 

 various chemical changes which pig iron undergoes in pud- 

 dling during its conversion into wrought iron. We therefore 

 at once decided to undertake this task, with the hope of 

 throwing some light upon this important operation. Fully to 

 investigate the progressive and interesting chemical changes 

 which cast iron undergoes during its conversion into wrought 

 iron, we took samples every five or ten minutes after the pig 

 iron had melted in the furnace. These chemical actions are 

 clearly defined in the furnace by the peculiar appearance 

 which the mass assumes as the operation proceeds. Before 

 describing the various chemical changes, the appearance of 

 the melted mass as taken out of the furnace, and its com- 

 position, we shall describe, with some detail, the analytical 

 processes which we have adopted to determine the various 

 elements which exist in pig and wrought iron, and in the 

 samples taken during the puddling. 

 R 



