1908.] Agents in the Oxidation of Amorphous Carbon. 251 
second flask was not inoculated with bacteria. Throughout the whole 
duration of the experiment, the control always maintained a lower temperature 
(0°38 C.), than that of the inoculated flask, and by means of a third thermopile 
it was proved to possess a temperature 0°19 C. lower than that of the 
incubator. 
For a period of 11 days the temperature of the control flask exhibited no 
upward tendency, while that of the inoculated flask rose from a point much 
below that of the incubator to nearly 0°4 C. above it, and steadily 
maintained that degree of heat. J¢ 2s thus clearly demonstrated that bacteria 
have a decided action upon coal, resulting in a distinct rise of tenvperature, and 
that this increase of temperature does not occur when the coal rs preserved from 
bacterial action. 
Some further experiments with the thermopile and galvanometer upon 
moist and dry coal emphasise these conclusions. At a temperature of 40° C, 
the coal moistened with distilled water and inoculated showed a difference of 
temperature of 1°25 C. above that of similar coal dried at 100° C. It was 
also found that at a temperature of 4° C., when the activity of the bacteria 
would be reduced almost to a minimum, the difference between sterile and 
‘non-sterile charcoal was inappreciable, amounting to only 0°03 C.; while at 
14° C, the amount registered was 0°19 C., which shows that the difference of 
temperature increases as the thermal conditions become more favourable to 
bacterial life.* 
Important additional evidence that the CO: production from the carbon 
is undoubtedly due to bacterial action would be afforded if it could be shown 
that the CO, is only evolved under conditions consistent with the life of 
these organisms. [ owe to Dr. F. F. Blackman the suggestion that it would 
be a critical test to show if the CO, production increased with a rise of 
temperature, and whether it goes up or down with causes that have the 
corresponding effects upon bacterial activity. 
With the object of elucidating this point, a further series of experiments 
was undertaken. Cultures of coal and charcoal were prepared under varying 
* In this investigation the actual measurements given must not be understood as repre- 
senting a quantitative analysis, which would be impossible under the conditions of treat- 
ment necessary to preserve the charcoal from contamination. The figures must be 
regarded only in a qualitative sense, and all that is claimed is that the titration method 
shows definitely that CO, is given off from the research material only when bacteria are 
present. 
From the equation C+ 0, = CO,+97650 calories we learn that 1 milligramme of CO, is 
produced by oxidation, with the evolution of 2:22 calories, and hence the rise of tempera- 
ture measured by the thermopyle is of the same order as the heat derived from oxidation. 
But as it is impracticable to suddenly destroy all bacterial action in a vacuum-flask and 
determine its rate of cooling, an exact equation cannot be obtained. 
VOL. .LUXXX.—B. U 
