186 
metastable, is very little stable. Also an equilibrium of Fe,C with 
C, which is founded on [V has never been observed. Moreover the 
assumption implies tbat a stable equilibrium already formed by a 
short interaction of CO with Fe would on prolonged action of CO_ 
pass into another equilibrium metastable towards the first and ex- 
hibiting a lower equilibrium pressure. This is contrary to the ideas 
of stable and metastable. 
The later researches of FarcKe*) have indeed but partly confirmed 
these first observations of ScHENck and his co-workers. It was con- 
firmed that on short interaction of CO with Fe a solid phase mixture 
was obtained that on beating in vacuum yields higher pressures 
than the mass formed by prolonged interaction of CO with Fe. The 
first pressures measured at different temperatures give a p-7-line 
situated at about 10—12° lower than the second one, whereas the 
latter gets very close to that of the equilibrium FeO, Fe, graphite, 
gas. As to the composition of the gas, it appeared, however, that 
this in both cases does not materially differ and, according to the 
temperature, varies from 52—61 °/,. 
Moreover, Farcke remarks that the first reaction product yields 
with HCI plainly hydrocarbons and leaves no residual carbon, 
whereas the iron ‘carbonised for a long time with CO yields little 
or no hydrocarbons and leaves much carbon. Also HiPerT and 
DikckMANN *) found that on heating ferric oxide in a current of 
carbon monoxide at temperatures from 720—800°, free carbon did 
not form until the preparation had taken up 6°/, of C (Fe,C contains 
6.6°/, C.) and was completely reduced. 
Hence it looks to me very probable that the higher pressures 
yielded by the iron carbonised for a short time, relate to the meta- 
stable equilibrium V (FeO, Fe, Fe,C, gas) and the lower pressures 
to the equilibrium III (FeO, Fe, carbon, gas). 
The projection of the four-phase lines on the T-x-plane. 
The change in the relation CO: CO, with the temperature in the 
different equilibria is schematically indicated by Fig. 9. 
Of this the line II] between 600° and 700° has been determined 
experimentally *); .the proportion ee varies from 52 to 64: 
ek COO 
Of the line II] ScpeNeK and FareKe announce the pressure but not 
Yale: 
2) Ber. d Deutsch. chem. Ges. 8, 1281. 
3) ScHenck and co-workers and Fatcke |. c. 
