240 Prof. M. C. Potter. Bacteria as [Jan. 18, 
This led to a wider consideration with regard to the action of bacteria upon 
certain carbon compounds such as coal and peat, and opened up the question 
as to whether it was possible that the vast supplies of carbon locked up in 
these formations could be utilised for plant life without the intervention of 
cirect combustion. That coal undergoes considerable wastage when exposed 
to the air is a fact very generally known, and in the case of large storages of 
coal the depreciation may reach a very high percentage. The conditions often 
preclude this loss being entirely attributed to weathering, and the question 
arises: are there then any other agents, such as bacteria, concerned in the 
process of disintegration ? 
In experiments dealing with substances of the nature of coal, peat, and 
charcoal, quite peculiar care had to be taken for the purpose of sterilisation, 
which proved to bea very difficult matter; while the chemical changes which 
take place during heating these substances to such a degree as was necessary, 
and the probable conservation of gases, were all points requiring due 
consideration for the elimination of possible sources of error. Further, the 
highly sensitive character of the electrical apparatus employed rendered 
special precautions necessary to guard against extraneous influences. It. will 
therefore be needful to give in detail, though as shortly as possible, the 
methods employed in conducting my research. 
The problem was attacked by three distinct methods, briefly stated as 
follows :— 
1. By passing a stream of air, freed from all trace of COs, over the’material 
subject to investigation and determining the presence of COs by titration 
with standard oxalic and hydrochloric acids. 
2. By determining the rise of temperature due to oxidation by means of a 
thermopile and galvanometer. 
3. By detecting, in the case of charcoal, the presence of calcium carbonate 
in the flasks inoculated with the bacteria. 
Charcoal, 
Pieces of ordinary wood-charcoal were pounded and passed through a 
double sieve, the first having a mesh of 1/10 inch, the second of 1/20 inch, 
so that in this way small fragments of fairly uniform size were retained 
between the two. A quantity of this charcoal was next heated by means of 
a metallurgical furnace to a white heat (about 1200°), in a crucible protected 
from any access of atmospheric oxygen. Heating to this point was a necessary 
treatment, as commercial charcoal is seldom sufficiently charred to drive o 
all volatile compounds. The entangled oxygen would thus, in the presence 
of an excess of carbon, be mainly converted into CO, and the calcium salts 
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