372 
CHEMISTRY: J. B. FERGUSON 
All of these with the exception of the measurements at 1458 were 
obtained from experiments in which platinum was present as a contact 
mass and the variations are probably due to analytical errors. The 
two measurements at 1458 were obtained from experiments in which a 
bare porcelain tube was used as a container and it is unlikely that 
equilibrium was reached in either case. An average of these two prob- 
ably will be very near the correct value. 
From these results the thermodynamical constant I for this reaction 
may be calculated by means of the equation 
- RT \nK = AHo - AF Tin T - ^ AFj - \AV^ P + IT (1) 
The additional data necessary has been well summarized by Lewis^ 
and his co-workers with the exception of the specific heat of S2 and 
and the value of AJ7o for the reaction +02 = SO2. The assumption 
that the former is the same as that of oxygen leads to the equation for 
the increase in heat capacity for the main reaction: 
Ar = - (1.375 - 0.0028 r-f- 0.000 000 937^2) 
The further assumption that Berthelot's^'^ value of 69400 cal. for the 
heat of formation of sulphur dioxide from its elements at room tempera- 
tures gives for the reaction 
i (Sr +02 = SO2) AlTo = - 34 195 cal. 
and for the main reaction 
CO + J SO2 = CO2 + i S2 AFo = - 25 915 cal. 
Substituting these values in equation (1) we have 
- i^rini^: = - 25 915 + 1.375 T\nT - 0.0014^ + 0.000 000 155r^ + IT 
In table 3 will be found the values of I calculated by means of this 
equation from the results found in tables 1 and 2. 
TABLE 1 
Equilibrium Approached from the CO-SO2 Side 
TEMPERATUKES 
Absolute 
Centigrade 
LogK 
1271 
998 
1.79 
1273 
1000 
1.73 
1273 
1000 
1.77 
1458 
1185 
1.13 
1463 
1190 
1.19 
