CHEMISTRY: J. B. FERGUSON 
371 
THE EQUILIBRIUM BETWEEN CARBON MONOXIDE. CARBON 
DIOXIDE, SULPHUR DIOXIDE, AND FREE SULPHUR 
By John B. Ferguson 
GEOPHYSICAL LABORATORY. CARNEGIE INSTITUTION OF WASHINGTON 
Communicated by A. L. Day. April 4. 1 91 7 
The value of a study of the equiHbrium between CO, C02, SO2, and 
S2 Hes not in the reaction itself, important as this undoubtedly is both 
to the scientific and technical worlds, but rather in the fact that frona 
such a study the free energy of sulphur dioxide, a quantity indispensable 
to a proper study of the chemistry of the sulphur compounds, may be 
directly obtained. That such an investigation has not heretofore been 
completed may be ascribed to the many difficulties which appear at 
the outset to block the way. The complex subsidiary reactions taking 
place at comparatively low temperatures are the source of many of these 
and would seem to have deterred Lewis and Lacey^ from continuing 
their investigations in this direction. These reactions may be thus 
summarized : 
CO + S ^ COS 
2 COS ^ CO2 + CS2 
CS2 ^ cs + s 
They rendered the ordinary stream methods of investigation useless 
since by these methods samples could not be obtained which had not 
reacted after leaving the equilibrium chamber. A semi-stream method 
devised by the writer obviated this difficulty and samples so obtained 
from equilibrium mixtures at 1263° abs. showed no evidence of any 
such reaction taking place. Since the velocities of these reactions 
greatly exceed that of the main reaction, which goes according to the 
equation : 
CO + i SO2 CO2 + i S2, 
the absence of the products of the former clearly indicated that by this 
method cooling effects had been eliminated. Details of the method will 
be given in the final paper. By it a given gas mixture may be heated 
for a given time at a given temperature and a correct sample of the 
same then obtained for analysis. It has also the added merit that 
if the temperature be properly varied the equiHbrium can be approached 
from either side. 
A few of the results obtained in this way are presented in the follow- 
ing tables, K being defined by the equation: 
