Forged Iron. Steel. Natural Steel. 65 



: , Forged iron perfefHy refined would confilt of the metal completely reduced, and con- 

 taining no foreign fubftance, not even charcoal. Such iron is not to be met with in the 

 market. The bed Swedifli iron always contains a portion of oxygene which has efcaped 

 the operations of the furnace and the refinery, and it is always contaminated by a dofe of 

 charcoal, very fmall indeed, but which perhaps it is impofllble totally to eradicate. 



Other circumftances likewife influence the qualities of iron, particularly with refpefl to 

 the fabrication of fteel. This metal, according to the nature of the ores which afford it, 

 may have the defefts of being brittle when cold, or brittle when hot. Thefe are refpec- 

 tively called cold-fliort, or red-(hort iron. We (hall not here difcufs the caufes which 

 produce thefe bad qualities* •, but (hall only remark that fuch iron, or its ores, affords bad 

 fteel, and muft therefore be carefully avoided. 



Steel is diltinguifhed into three kinds :— natural fleel ; fteel of cementation ; and cad 

 fteel. 



* Cetjcerning Natural Steel. 



THE fteel obtained immediately from the ore by fimple fufion. Is called natural fteel. 

 It is likewife diftinguiftied by the name of German fteel, becaufe it comes principally 

 from Germany. 



Whether the crude iron (hall afl"ume the nature of bar iron, or of fteel, depends on cir- 

 cumftances } but thefe are not difficult to be explained, from the doftrine already laid 

 down. 



Grey crude iron is alone proper to afford fteel ; for which purpofe it is requifite that 

 the oxygene it contains fhould be feparated, and the coal from which . its grey colour 

 arifes ftiould be intimately combined with it. The converfion of the crude iron into fteel 

 depends on thefe procefTes f . 



Hence it follows as a leading rule, that no attempts muft be made to convert the white 

 crude iron into fteel in this way, notwithftanding it may be capable of affording excellent 

 bar iron. The firft operation muft be conduced in fuch a way as to afford grey crude 

 iron, by adding a greater proportion of coal in the charge of the furnace. 



The appearance of crude iron is often deceitful with refpeil to its nature. The grey 

 crude iron in plates or fmall portions, fuddenly cooled, has the colour of the white crude 

 iron. But the nature of thefe irons may be afcertained by the fimple procefs defcribed at- 

 the end of this memoir. 



When a proper crude iron is in readinefs, it is necelTary, in order to convert it into bar 

 iron, that it fhould be much more expofed to the aclion of the air by frequent ftirring, and 

 by removing the fcorise ; but when fteel is defired, it is lefs expofed, and fuffered to remain 

 covered by thofe fcori*. In the former procefs the charcoal is burned by the contadl of 

 the air, and the iron is left confiderably more pure ; but in the fecond the charcoal is pre- 

 ferved ; part of which combines with the oxygene which ftill remained in the iron, and 



•CoM-fliort iron is aflforded by ores whicli contain a fmal! portion of phofphoric acid, whicli combines with 

 the metal in the ftate of phofphorus. Red-ftiort iron, which is much lefs common than the other, contains 

 arfenic; but it is probable that the other femi-metals may produce the fame effeft. AW of the aulhors^ — Pro- 

 tably the volatile metals may moft eminently conduce to this effeft. N. 



\ See Ehilof. Journal, I. 318. 



Vol. II.— Mat 1798. K fcrves 



