l86 On the AJjaying of Iron Ores 



than to the carbon united with it, carbonic acid was form- 

 ed. A review of thefe expei'iments leads to another con- 

 clufion, that, without the prefence of carbon, either in 

 chemical union in the ore, or attrafted from the ignited gas 

 by the particles of metal, crude iron will not feparate from 

 the ore or {lone ; and that, in proportion as the metal is ex- 

 pofed to inhale this principle, its produce is increafed and its 

 quality improved. 



It will further appear obvious, from the various natures of 

 icorice which the different iron-ftones aflbrd when fufed per 

 fc, that there exifts a want of mixture in moft of them to 

 form, when fufed, a fluid fo fufficienilv divided that no por- 

 tion of iron may be retained, either in a metallic Hate, or in 

 that of an oxyde. This deficiency of mixture is greateft in 

 the liiiceous iron-ftones, lefs in the argillaceous, and leaft of 

 all in the calcareous. The principle, therefore, I proceeded 

 upon was, to afcertain what proportion of additional mixture, 

 and of what nature, was neceflbry to give the proper equi- 

 librium to form a tranfparent fcoria. When filex predomi- 

 nated, it was found that a major proportion of calcareous 

 earth, in the folvent or flux, fupplied the natural deficiency ; 

 and that the whole contents in iron were juftly revived, and 

 fully faturated with carbon : when at any time it was wiflied 

 to revive the metal, contained in fuch ores, pofl'efling ftrength 

 with carbonation, I found that this could be eafily efFe6lcd, 

 in all proportions, by the addition of calcareous earth with 

 a mixture of pure clay. In fliort, in every experiment I have 

 \nade with ores, the various natures of lime-llones, or chalk, 

 ■with certain proportions of bottle glafs, have been found 

 capable of reviving the iron contained in all the ores which 

 have come under my knowledge, and of conferring upou 

 their refpeftive pr* duels every degree of ftrenoth and fufi- 

 bility *. In order to form an accurate judgment of the ten- 

 dency 



'■'•' Although I have frequently had occafion to mention the combina^ 

 laon of clay with iion-ftone, as the mixture which in fufioa conveyed 



ftitnstl* ' 



