Mixtures of the solid phases in equilibrium with carbon monoxide and dioxide were heated in a porcelain tube at a definite temperature until equilibrium was produced, and the gas was then pumped off and analyzed. The results which were obtained are given in the following tables, and represented graphically in Fig. 121.

Solid Phases: Fe3O4; FeO.

No. Tube filled
with		 Duration of
the experiment
in hours.		 Temperature. Percentage of
CO2 CO
1 CO 14 600° 59.3 40.7
2 CO 15 590° 54.7 45.3
3 CO2 16 590° 64.6 35.4
4 CO 24 590° 58.4 41.6
5 CO 22 730° 67.7 32.3
6 CO2 22 730° 86.1 31.9
7 CO 22 750° 68.4 31.6
8 CO2 22 610° 64.9 35.1
9 CO 23 420° 56.0 44.0
10 CO 47 350° 65.6 34.4
11 CO2 46 350° 72.8 27.2
12 CO 53 350° 64.0 36.0
13 CO 18 570° 53.4 46.6
14 CO 19 680° 60.5 39.5
15 CO2 24 540° 55.5 44.5
16 CO 21 630° 57.5 42.5
17 CO2 17 690° 65.5 34.5
18 CO2 17 670° 67.0 33.0
19 CO2 24 410° 58.5 41.5
20 CO 24 490° 51.7 48.8
21 CO2 23 590° 54.4 45.6
22 CO2 4 950° 77.0 23.0
23 CO2 15 850° 73.4 26.6
24 CO 8 800° 71.2 28.8
25 CO2 24 540° 56.7 43.3

Solid Phases: FeO; Fe.

No. Tube filled
with		 Duration of
the experiment
in hours.		 Temperature. Percentage of
CO2 CO
I. CO 15 800° 35.2 64.8
II. CO 18 530° 29.1 70.9
III. CO 13 880° 30.2 69.6
IV. CO2 24 870° 32.3 67.7
V. CO 18 760° 36.9 63.1
VI. CO2 16 820° 34.7 65.3
VII. CO2 18 730° 41.1 58.9
VIII. CO 18 630° 34.9 65.1
IX. CO2 17 630° 61.6 58.4
X. CO 18 540° 25.0 75.0
XI. CO2 25 540° 36.5 63.5

As is evident from the above tables and from the curves in Fig. 121, the curve of equilibrium in the case of the reaction

Fe3O4 + CO = 3FeO + CO2

exhibits a maximum for the ratio CO : CO2, at 490°, while, for the reaction

FeO + CO = Fe + CO2