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LV. Oti tbe different Vroport'ions of Carbon which cr,njtituii 

 the various Qualities of Crude Iron and Steel. By Davi D 

 MusHET, Efq. of the Calder Iron Iforks". 



JlT is of confiderable importanee to the manufaflurer to 

 afcertain the abfolutc portion of charcoal which in his pro- 

 cefs becomes united with the metal to form caft iron. Having 

 once admitted the h&, that it is in the ratio of the carbon 

 prefented to the metalUc particles that he obtains a deter- 

 minate quality of crude iron, experiment will enable him to 

 deduce, that in manufafturing the richeft natures of iron his 

 produce from the ore will be more, by the extra quantity of 

 carbon nF.ceflTary to conftitute this quality, than when the in- 

 ferior numbers of iron are produced. In all cafes, therefore, 

 in making caft iron, confiderable quantities of the coal be- 

 come united with the iron, forming, by weight, a portion 

 comparatively great. 



From the ufual procefles hitherto employed in manufac- 

 turiniT bliftered ftcel, the pofitive quantity of carbon which 

 became united with the iron never became an objeft worthy 

 of the attention of the manufafturer. It was fufficient to him 

 that his bars poflefled blifters fufficiently large and prominent 

 to afiiire him that his fteel was fufficiently converted. The 

 unerrinir teft of pratlice through a long feries of operations 

 coniimied the correftnefs of this deduiSlion ; and it mull 

 have appeared a matter of little importance to the formation 

 of fteel, that its dired operation of principle Ihould be deve- 

 loped, or the laws which regulate its affinity in cementation. 

 No additional facl was ncceftary to the production of caft 

 fteel. The finiple fufion of bar fteel, regulated by fuch cir- 

 cumftances as practice, and the various ufes to which this 

 ftcel is applied, was all that was nccellkry to be known ; the 

 affinity of iron for carbon, and the various proportions in 

 which it exifts with the metal, forming the difierent qualities 

 of fteel, here met with no elucidation. 



On the contrary, we ftill find that the union of iron and 

 charcoal to form llcel, is a matter of doubtful opinion among 

 manufaclurers, and the weight gained by its cementation 

 generally denied. 



It is only hitely that a procefs has been brought into ufe 

 for making caft (leel, which has for its bafis or principle the 

 direct proportions of carbon neceflary to form ftcel, illuftra- 

 tive at tb!^ fame time of that beautiful phjenomenon of afii- 



* Commiinicared by the Author. 



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