to On the Materials nfed 



exifting as melting pig-iron ; and which is always effected 

 previous to fcparation— of courfe before the mixtures ought 

 to come in contact with the blaft. 



To thefe general data, the following quality of coal found 

 in different places in England and Wales claims exception. 

 This coal is compofed of a very fmall proportion of bitumen, 

 and contains more carbon than any of the Scotch coals 

 hitherto difcovered. To the purity of the fplint-coal it unites 

 all the foftncfs and combuftibility of wood. The effects 

 produced by it in the blaft-furnace, either as to quantity or 

 quality of caft-iron, far exceed any thing in the hiftory of 

 the manufacture of that metal w'.th charcoal. At prefent 

 there is one furnace in Wales that yields 60 tons of pig-iron 

 upon an average weekly. 



In preparing pit-coal for the blaft-furnace, well under- 

 stood among manufacturers by the term coaking, flat fur- 

 faces are appropriated. Thefe are firmly beat and puddled 

 over with clay, fo as to pafs the neceffary cartage without, 

 furrowing or loofening the earth. Thefe fpaces form fquares, 

 more or lefs oblong, and are called hearths ; upon which the 

 pieces of coal are regularly placed inclining to each other. 

 Great care is taken to place each piece upon the ground 

 layer on its acuteft angle, in order that the lead; furface pof- 

 fible may come in contact with the ground. By this means 

 large interfaces are preferved for the admiffion and regular 

 communication of the air neceffary to excite and effect com- 

 plete ignition. 



The quantity of coaks charred in one heap or hearth, is- 

 various at different, and even at the fame works. Forty 

 tons of coals is amongft the fmalleft fires, and fome hearths 

 again will admit of 80 or 100 tons. The length of the fire 

 is in proportion to the quantity of coals built : the breadths 

 and heights are alfo fubject to no determinate flandard ; 

 but are from 30 to 50 inches high, and from 9 to 16 feet 

 broad. In building each fire, they rcfervc a number of vents 



reaching 



