Ohfervatirts on Iran and Steet. 53 



required for ufe. This is alfo called fhear fteel, and is 

 fuperior in quality to the common tilted fteel. Caft fteel 

 is alfo made from the common bliftered fteel. The bars are 

 broken, and put into large crucibles with a flux. The cru- 

 cible is then clofed up with a lid of the fame ware, and placed 

 in a wind furnace. By the introduction of a greater or 

 fmaller quantity of flux, the metal is made harder or fofter. 

 When the fufion is complete, the metal is caft into in- 

 gots, and then called ingot fteel ; and that which afterwards 

 undergoes the operation of tilting, is called tilted caft fteel. 

 The caft fteel is the moft valuable, as its texture is the moft 

 compact, and it admits of the fineft polifh. Sir T. Frankland 

 has communicated a procefs, in the Tranfactions of the Royal 

 Society*, for welding caft fteel and malleable iron together j 

 which, he fays, is done by giving the iron a malleable, and 

 the fteel a white heat j but, from the experiments which 

 have been made at my requeft, it appears, that it is only foft 

 caft fteel, little better than common fteel, that will weld to 

 iron : pure fteel will not ; for, at the heat defcribed by Sir 

 T. the beft caft fteel either melts, or will not bear the ham- 

 mer. It may here be obferved, as was mentioned before, 

 that fteel is an intermediate ftate between crude and malle- 

 able iron, except in the circumftance of its reduction being 

 complete j for, according to the experiments of Reaumur 

 and Bergman, fteel contains more hydrogen gas than caft 

 iron, but lefs than malleable iron ; — lefs plumbago than the 

 firft, but more than the latter ;— an equal portion of man- 

 ganefe with each ; — lefs filiceous earth than either ; — more 

 iron than the firft, but lefs than the fecond. Its fufibility is 

 likewife intermediate between the bar iron and the crude. 

 When fteel has been gradually cooled from a ftate of igni- 

 tion, it is malleable and foft, like bar iron ; but when ig- 

 nited and plunged into cold water, it has the hardnefs and 

 brittlenefs of crude iron. From the foregoing facts we are 

 juftified in drawing the fame conclufions with Reaumur and 

 ♦ Phil.Tranf. 1795. 



E 3 Bergman, 



