ManufaBure ofPig-Iron tvith Pit-Coal. 41 



In 34 hours 18 of the above charges would have been 

 Confumed, and nearly 3 tons of forge-pigs produced. 

 The total quantity of char ufed for 



the quantity would be - a X 18 = 35 cwti 



The total quantity of iron ore - 7x18 = 1 26 



ofiron-ftone i^ x 18 = 9 



— oflimeftone - { X \^ = 3j 



Wc find therefore that 12 cwt. or 13441b. of the charcoal 

 of wood, produces of forge pig-iron 2240 lb. or i ton j 

 and that 126 cwt. of Lancaftire ore -j- 9 cwt. ofiron-ftone, 

 yielded of metal 60 cwt. This quantity, by an eafy mode 

 of calculation, will be found to be at ihe rate of 44*4 per 

 cwt. 



When carbonated crude iron was produced, the charge 

 was, 200 cwt. of wood char, 5 cwt. of ore, 4 cwt. of iron- 

 ftone, 141b. of limeftone. 



The weekly quantity was ahvays di niniflied in proportion 

 to the reduction of the quantity of ore ufed. In 24 hours the 

 quantity of the pig-iron produced, averaged 48 cwt. of carbon- 

 ated crude iron. As this is the quality of metal which ferves 

 as the bafis of the calculation in Number XX. of the Philo- 

 fophical Magazine, it will be the moft proper ftandard to 

 compare the widely different effefts produced by wood and 

 pit-coal. In that Number a table is given of the quantities 

 of crude iron each variety of cokes produce, and which, for 

 the fake of immediate comparifon, I fliall here again infert. 

 1 ton, or 22401b. clod-coal cokes produces 



of carbonated iron - - 1040 lb. 



1 ton, or 22401b. fpliat-coal cokes - 840 



2240 mixed coals - - 70a 



I ton, or 22401b. of ^charcoal of wood, ac- 

 cording to the proportions furniflied above, 

 will produce of carbonated iron - 2985 



1 ton, or 22401b. of the fame, will produce 



of oxygenated crude iron for forge-pigs 3718; and 

 I ton of carbonated pig-iron will require 



of the cokes of clod-coal - - 4824.61b. 



• fplint-coal - 5973-3 



mixed - 7^47-5 



' wood charcoal - 1680 



Vol. VII. G From 



