646 
rature, but still depends on the total pressure; consequently in the 
graphical representation of fig. 1 not one line, but a series of lines, 
which each hold for a definite total pressure, are obtained for this 
equilibrium. If we now determine the situation of the line of equili- 
brium for one atmosphere total pressure in the graphical represen- 
tation, it appears that it ascends very rapidly, and intersects the 
two lines of Baur and GrässNrr. It is indicated dotted in figure 1. 
The equilibria on the left of the minimum and on the left of the 
maximum of Baur and GrässNeR are metastable with respect to 
carbon; in this region carbon can be deposited; this can account for the 
branch of the Fe,O0,—FeO equilibrium that ascends towards the right, 
the more so as the setting in of the generator gas equilibrium is acce- 
lerated by iron oxides. Of the branch of the Fe—FeO-equilibriam 
descending towards the right no sufficient explanation is to be 
given in my opinion. The equilibrium FeO + CO 2 Fe + CO, has 
been later examined by Scuenck ; the minimum was not found back 
by him; his observations are indicated in fig. 1 by squares!). 
Through his points the line CD has been drawn. Also FaLCKE’s 
determinations *) vield a line without minimum (in fig. 1 three points 
are indicated by circles), which, however, ascends more abruptly 
than CD and is in better agreement with the determinations at higher 
temperatures (line D# through Baur and GLAsSNER's points). 
No other data of the equilibrium Fe‚O, + CO 28 Fe 0 + CO, are 
known to me than those mentioned by Baur and GLAssner. The 
line AB has been drawn as well as possible through the observations 
at the highest temperatures. 
The. remarkable conelusion to which these considerations lead, is 
that the lines for the two equilibria intersect. And this must be the 
case both when for the equilibrium FeO + COZ Fe + CO, we 
consider the observations of ScHenck (CD) as accurate, and when 
we consider those of Faucker (circles in fig. 1) and those of Baur 
and GLAssneR at the highest temperatures (DE) as valid. 
If this intersection occurs, it follows from this that below the tem- 
perature of the point of intersection FeO must be a metastable compound. 
This is easy to see, as in this point of intersection Fe, FeO, and Fe,O, 
occur in equilibrium by the side of the gasphase, and there also 
exists, therefore, equilibriuin between the three solid phases without 
gas. Hence at lower temperatures FeO will continue to be either 
metastable, or break up into Fe + Fe,Q,. 
Below the temperature of the point of intersection the equilibrium 
\) ScHENcK, Ber. 40, 1704 (1907). 
?) FaLcKE, Zeitschr. f. Elektroch. 22, 121, (1916). 
