18 On the Materials ufsa* 



The advantages that charcoal poffeffes, beyond thofe of pit- 

 coal, for the manufacturing of crude iron, are derived from 

 the purity of its component parts, and the fuperior quafitity 

 of unalloyed carbon it affords to the iron. This principle 

 is prefented to the metal free from the combination of clay, 

 lime, fand, and fulphur; with which pit-coal frequently 

 abounds. A determinate quantity of charcoal by meafure, 

 will fmelt and convey principle to three times the quantity 

 of iron that can be done by the fame meafure of pit-coal 

 coaks. Its greateft and moft ufeful property, however, 

 feems to be developed in the refinery fire, and fimilar bar- 

 irort operations ; where it manifefts in the moft evident 

 manner its fuperiority over pit-coal, by ihortening the 

 tedious proceffes of the forge, diminifhing the waftc, and 

 affording a much fuperior quality of iron for all the pur- 

 pofes of fubfequent manufacture. 



Pit Coal, 



No fooner had the confequences of the general diminution 

 of wood, for the purpofe of making charcoal, been felt by 

 individuals, whofe intereft it was to fupport the fabrication 

 of iron, than their violent prejudices were laid afide againft 

 the ufe of pit-coal, and this mineral combuftible fubftance 

 was brought forward, and eftablifhed as the bafis of a profit- 

 able and ufeful manufacture. 



Pit-coal has hitherto been better known, and its ufeful- 

 nefs made more fubfervient to the purpofes of life and of 

 manufacture in Britain, than in any other country. This 

 valuable fuel is generally found in flrata of various dimen- 

 lions, afid of various inclinations from the parallel of the 

 horizon. It is alio found, though fcldom, in vertical maffes 

 irregularly diffufed, and lefs extenfive than the former. 

 Regular ftrata widely extended are found from 3 to 10 feet in 

 thicknefs ; thofe moft commonly met with are from 3. to 6 feet*. 



* There is at Dyfart in Fifelhire a regular ftratum of coal upwards of 

 ZAfvet t ick, and is the thickeft evut' beard of in this CQuntry. 



The 



