358 On Primary Ores of Iron. 



coal, iflues from the furnace highly oxygenated — a num- 

 ber of globules deflagrating fo foon as it comes in contact 

 with the air. 



If, in order to correct the quality of the iron/a portion of 

 the iron-ftone is taken off=i box, or 60 lb. let the produce 

 of this weight be eftimated at 40 per cent, then the quantity 

 of metal taken- from the total 201, will be equal to 24, 

 leaving for metal produced at each charge 177 lbs. inilead 

 of 168, as in the former cafe when the iron was fuper-car- 

 bonated. — Additional quantity of metal t, lbs. 



Quantity of concrete oxygen, reckoned at 22 per cent, 

 nearly equal to 2 pounds weight. 



Small as this quantity may appear to be, yet, on many 

 occafions, a furnace will not admit of the addition without 

 altering the quality of its iron from the one extreme to the 

 other. The manufacturer, therefore, finding his operation 

 with ores fo fubtle and precarious, frequently abandons their 

 ufe, in the firm belief that their application, in quantity, is 

 incompatible with the exiftence of good melting pig-iron; 

 whereas, had the ore received a proportion of fuel adequate 

 to its fuperior richnefs, it is at leaft queftionable whether the 

 exact fame confequences would have been entailed : even in 

 the cafe of iron-ftones, the manufacturer ought to confider 

 the quantity of iron contained in the ore, as alfo the nature 

 of the various mixtures, in order to enfure to himfelf a pro- 

 duce of carbonated crude iron. 



There are two ways which would moft likely be attended 

 with the happieft effects in producing melting pig-iron from 

 primary ores of iron with pit-coal, advantageous to indivi- 

 duals, and to the improvement of the bufinefs in general : 

 the one, by a procefs fimilar in its principles of preparation 

 to that at prefent practiled for iron-ftones; the other, by de- 

 oxygenating the ore before it is introduced into the blaft 

 furnace. To enfure fuccefs in the former of thefe operations, 

 the following requijlites would be neceffary. 



I ft. A narrow conftructed furnace, of an unufual height, in 

 ^ defcendina: 



