107 
solution ? I suppose it is assimilated to the substance of the 
plant, together with the other nutritive ingredients which 
the sap holds in solution. No, that cannot be ; for in order 
to render carbon fit to be assimilated, it appears to be neces- 
sary that it should previously be combined with oxygen, and 
afterwards separated from it." It is in this second mode of 
the reception of carbon that Liebig differs from De Candolle, 
whose opinions these of Mrs. Marcet's are ; and he thinks 
that the quantity of carbon received from the air has not been 
duly appreciated by naturalists. Boussingault proved in 
1838, that if full-grown plants, endowed with perfect organi- 
zation, be transplanted into a soil deprived of every particle 
of organic matter, by subjecting it to a red heat, they do 
not only receive nitrogen, but also carbon, and although they 
had nothing but water and air for their whole food, neverthe- 
less they flowered, and produced seed to perfect maturity ; his 
experiments were upon clover, peas, and oats. 
CARBON. HYDN. OXGN. AZT. 
Peas sown ... 1,072 contg. grains of 0.515 0.069 0.443 0.055 
Crop 4,441 Do. 2.375 0.284 1.680 0.110 
3.369 Gain on culture 1.860 0.215 1.237 0,055 
In this experiment 1,072 grains of pea-seed gained 3,369 
grains of organic matter in 99 days of vegetation during the 
hottest months of the year. The plants of clover were taken 
from a field which had been sown the previous year. 
The clover was transplanted into sand previously calcined 
on the 28th May, and sheltered from dust floating in the 
air. It first languished, but soon afterwards showed remark- 
able vigour. On the 15th of July it flowered, and its colour 
was of a beautiful flesh red. On the 1st of August, it was 
taken up, and it was then obvious that the roots had not 
grown any. 
