393 



the two-phase regions in the system Fe — CO — CO, (resp, Fe — H, — 

 H,0), iiiid this has rendered it |)0ssible to elucidate the reduction 

 processes, which e. g. take [)lace in blast-furnaces, from beginning to 

 end by means of a graphical representation ^). 



For this purpose we ciioose one of onr last two tignres, e. g. the 



Fig. 9. 



more probable one, fig. 7, and draw in tiiis the line pQ for the 

 eqniiibrinm 



CO, + C ^ 2C0 



as this is situated in the blast-furnace. 



Thus arises fig. 9, and the processes that take place in tlie blast- 

 furnace are read from the graphical representation bearing in mind 

 that then tlie course of this line of e(|uilibrium should be followed 

 through the different regions given here. We then start from point 

 P and end in point Q. 



In this way we see that theoretically the reduction from Fe,0, to 

 FejO^ takes place for the first time in the point a. then in b the 

 reduction from Fe^O, to FeO, in c that from FeO ro Fe, and finally 

 in d melting of the iron. Hence we shall remain in each of these 



') The Figure can easely be completed considering tlie formation ot cementit 

 t)ut this is omitted liere intensionally. Reindkr« (Proceedings 19, 175 (1916) has 

 already indicated partly the equilibriums with cementit. 



