336 
PRESENCE OF CARBON IN LIVING PLANTS. 
o that all communication between the mould and the surface was 
effectually prevented. I now filled a glass-receiver with rain water, 
which had been previously boiled, and inverted the pot into it, and 
plunging the whole under water I brought it to an upright position, 
the receiver standing over the plant full of water, which was pre¬ 
vented running out by the lower rim of the bell-glass being immer¬ 
sed in the trough round the pot. I then injected oxygen gas into 
the glass, till nearly the whole of the water was out, and with a small 
syringe forced a quantity of lime water under the rim of the glass, 
until I considered the water which remained in the trough suf- 
ficently impregnated with it. I used lime water, as affording the 
readiest means of detecting any carbonic acid gas that might be given 
out by the plant. I then placed the pot in a window, not exposed to 
the sun, and as this was done in the morning, I had an opportunity 
of observing if any carbonic acid were given off during the day ; but 
in the evening I was unable to discover any sign of its having been 
evolved. The next morning I found the surface of the lime water 
covered with a thin film, which could only have arisen from the lime 
which was held in solution having imbibed carbonic acid. Now as 
all communication with the external air, and also with the mould in 
the pot was entirely cut off, the only so,y|^from which the carbonic 
acid could have been derived was the plant. It will perhaps be need¬ 
less to state, that the plant was perfectly healthy without a sign of 
decay or any of its parts, and that the oxygen used had been 
thoroughly washed in lime water, so as to destroy every trace of car¬ 
bonic acid in it. 
Gosport, April 23rd, 1834, 
T. HARHCASTLE, PRINTER, CHURCH-STREET, SHEFFIELD. 
