248 Prof. M. C. Potter. Bacteria as [Jan. 18, 
measure of the electromotive force, and in reality due to the difference of 
temperature between the two flasks, the terminals of the thermopile were 
interchanged, that is, the terminal in the inoculated flask was placed in 
the sterile flask and vice versé. The galvanometer then indicated an equal 
current in the reverse direction (after a sufficient time had elapsed to 
counteract the effects due to handling), thus proving that the deflection 
was due to the difference of temperature and not to any accidental error in 
the apparatus. 
By measurement, the maximum deflection indicated by 38 scale-divisions 
corresponded to a rise in temperature of 0°19 C., and this temperature 
was maintained for the further period of a week, when the apparatus was. 
taken down. This conclusively establishes the fact that a measurable rise of 
temperature takes place wm charcoai, owing to oxidation through the action of 
bacterva. 
Lamp-black. 
Experiments were also undertaken with commercial lamp-biack as another 
source of amorphous carbon, the results of which may be briefly stated. 
This substance in the first instance was heated to a white heat in the 
metallurgical furnace ; afterwards it was soaked in aqua-regia for nine days, 
then carefully washed in distilled water, and any excess of acid still 
remaining neutralised with metallic sodium cut from the centre of a block 
to ensure the absence of any naphtha. The lamp-black so prepared was: 
treated in the Cloéz flasks in the manner described for charcoal, and some 
were inoculated with bacteria, while the rest were kept as controls. For a 
period of 24 days the flasks inoculated with bacteria showed, upon titration, 
the evolution of a small quantity of CO, (17 milligrammes) as compared with 
the non-inoculated flasks. 
The result of the titrations agreeing so closely with those obtained in the 
case of charcoal, it was not deemed necessary to determine the rise of 
temperature by the thermo-electric method. 
Peat. 
A set of experiments upon peat, corresponding to those already described. 
for charcoal, was carried out in an exactly similar manner, except that the 
peat was not calcined; it will not, therefore, be necessary to do more than 
. briefly state the results. The peat was obtained from the Solway district, 
and was of the ordinary dried kind such as is used for fuel, Sphagnum being 
the chief constituent. 
