

On tU Component Tarts of Iron-Jlbn-es. 209 



a proportion of oxygen to the metal, chiefly before fepa- 



ration is effected. 



Does it not then unqueftionably follow, that if the quan- 

 tity of charcoal in the furnace formerly was fufncient to 

 take up the oxygen exifting in the ore, and to afford car- 

 bonated crude-iron, that if a further quantity of this princi- 

 ple is added, by whatever means, part of the charcoal which 

 formerly went to carbonate the iron now combines with the 

 fuperadded oxygen to form carbonic acid; of courfe the 

 metal will be deprived of its carbon, become white in the 

 frafture, and may then juftly be denominated oxygenated 

 crude-iron. The fame application to principle would alfo 

 inform the merely practical man, that when iron-ftone is 

 completely deprived of thofe fubftances which aflume tbe 

 gafeous ftate by the combination of caloric at a moderate 

 temperature, it is then fufficiently prepared for the furnace. 

 This is always indicated by the colour which the (tone 

 aflumes varying from a brown to a dark claret. Blues 

 always fucceed this ihade ; and the fmalleft appearance of 

 blue, however light, is a certain fign that the external air 

 has made an impreflion upon the particles uf metal, by 

 fuperoxygenating them. Inftead therefore of expelling a 

 further quantity of heterogeneous matter, a principle is added 

 the moft noxious and deftruftive to the exiftence of iron in 

 a metallic form. 



The phenomenon of iron-ftone becoming heavier in the 

 fire, would no longer be explained by afluming vague af- 

 fertions incompatible with and inadmiflible to common 

 fenfe. Upon finding two pieces of iron-ftone in the fame 

 fire, which have to appearance been affected in a widely 

 difterent manner by the heat ; the one heavy, of a black 

 blueifh colour ; the other light and porous : the practical 

 man would now no longer fay that the metal from the 

 porous piece had efcaped by thefe pores, and entered into 

 the ponderous one ; and that the accumulation of weighs 

 in the latter was entirely owing to it abftra&ing the metal 

 Vol. III. P froA 



