40 On the Origin and Progrcfs bf the 



pig-iron with pit-coal, it may be gratifying to make si fexif* 

 obfcrvatioiis upon the procefs conducted with the charcoal of 

 wood. The fuperior purity of the Carbonaceous matter in 

 wood, nnd its greater degree of inflammability, render this 

 operation more fimple than that performed with pit-coal. 

 The former properly admitted of a fmall furnace being ufcd ; 

 the latter required a much lei's degree of blatt to purifv the 

 ore, and give out falisfacJtory refults both in the quantity and 

 Cjuality of the metal. Few charcoal furnaces exceeded the 

 height of 20 feet, and nvmv of them were from 12 to 15, 

 A very hnail column of blail was ncceflary to excite igni- 

 tion, and produce the redu6tion of the materials. Lanca-^ 

 iliire and Cimiberland ores were chiefly in ufe ; their fuperior 

 richnefs in iron rendering them foon metallifed when in con- 

 taft with ignited charcoal of wood : 13 to 24 hours were 

 ludicicnt for this purpofe, according to the fiz^e of the fur- 

 liacc and the quality of the pig-iron wiflied. Not fo in the 

 manutacluring of coke pig-iron at prefent : the inferior 

 quantity of iron which is contained in iron-ftones, the im- 

 purity of the carbonaceous matter in pit-coal, eftablidies a 

 nuich lefs degree of aiTuiitv betwixt the metal and the prin- 

 ciple of its reduction. The oxygen of the iron-fl^one is 

 longer in being removed : this requires an additional period 

 df contact. To procure this, the furnace muft be heightened 

 to 35 or 40 feet, and the dei'ccnt of the materials protracted 

 tt) three days. 



It will be i^ropcr to exhibit the comparative eficcts pro- 

 *!uced by the char of pit-coal and that of wood. The fol- 

 louing particulars will ferve as data to make a calculation of 

 llic relative effects of the two different fuels with a charcoal 

 furnace of 26 or 27 feet high, 9 feet wide at the boflies, 

 and blown by two I'l- inch pipes placed along tide of each 

 tvlher at the tuyere of the furnace. To make forge-pigs with 

 this furnace, the following proportions have by experience 

 been found rcquifite for each charge : 

 2 facks of tharcoal of 112 lb. each 

 7 meafures of well dried Lancalhirc ore, each x 1 zlb. 

 Kaw iron-floriC _ _ _ _ 



Limefione. - - - 



