^6 On the ManufaBure of Crude Iron, 



immediately correal the pernicious dfefts of the filcx, and 

 facilitate the carbonation of the metal ; but will not confer 

 any great degree of additional ftrcngth. Lime may be added 

 to fuch cxcei's as to render the continuity of the particles of 

 iron fo fmall as to be eafily divided into granulated maflcs, 

 forming a true plumbago. 



From a confidcration of thefe rcfults, wc are led to attri- 

 bute to calcareous earths the property of facilitating the car- 

 bonation of the metfil where an improper combination exifls; 

 which property is derived from the carbon of the acid with 

 wliich they arc neutralifed. To argillaceous ores we afcribe 

 ftrcngth, without having the tendency of deftroying the 

 carbon, merely becaufe ihefc ores contain a very confiderablc 

 portionof lime ; their union counterafts the natural fufibility 

 impofed by lime, and at the fame time is pvodufiive of 

 flreuirth. Siliceous iron ftoncs are viewed lefs favourably, 



to - 



being nearly dellitute of lime; the iron in the furnace 

 varies in principle from the development of its mixtures, 

 and only depends upon tlic quantity of carbon furniflied by 

 the fuel to become faturated with a fufficicncy to conflitute 

 fufibility. 



The exclufive predominancy of lime and filex apart tends 

 in the fmelting proccfs to reduce crude iron lo its two 

 grcatelt extremes of quality, carbonation and oxygenation; 

 both of which Hates are equally deilitute of ftrenglh. Clay 

 afts as the reflorer of thefe diiproportions, and by a happy 

 combination produces the medium of the two extremes, 

 ^vhich is flrcn";th and undiminiflied quality. 



Were filiceous iron Hones univcrfally combined with a 

 larger portion of oxygen than the other clafl'cs, another clue 

 would be fumifhcd to explain why iiliceous mixtures were 

 lefs congenial to the cxifience of carbon in the blaft furnace, 

 than thofe of lime and clayj and why tlic metal obtained 

 fivom the former is always more oxygenated with the fanxe 

 portion of fuel than that obtained from the latter. Although 

 I am convinced tl;at this fi-equcntly is the cafcj yet, a? I have. 



net; 



