{ & ) 
lime and five of silica; the latter thirty of carbonate 
of lime’ and fourteen of silica. 
tz 
THIRD. EXPERIMENT. 
This.was made to determine whether vegetables, 
the produet. of a soil having in it no silica, would, 
notwithstanding, partake of that earth. Plants were 
accordingly taken from Reculey de Thoiry, (a soil 
altogether calcarious,) and the result Was a Wry 
small portion of silica. 
‘These experiments, says Chaptal, leave little if 
any. doubt, but that vegetables. derive the earthy — 
matter they contain from, the soil in which they 
grow.( 1) 
Ii, Of water, as an agent in vegetation. 
Seeds placed in the earth, and.in a temperature 
above the freezing point, and watered, will deve- 
lope; that is, their lobes(2) will swell, their roots 
descend into the earth, and their stems rise into the 
air, But without humidity, they will not germi- 
nate; or deprived of humidity after germination, 
they willl perish. When germination is complete 
and the plant formed, its roots and leaves are so or- 
ganizedas to absorb water. ‘The experiments of 
Hales prove, that the weight of plants is increased 
in wet and diminished in dry weather ; and that in 
the latter, they draw from the atmosphere, (by 
(1) Scheder maintains the doctrine, that the earths found in plants are created 
there by the process of vegetation. His essay on this subject was crowned by the 
academy of Berlin, in 1801. His experiments were the first to determine the dif- 
ferent quantities of silica found in different kinds of grain. 
(2) Moisten a bean in warm water, and detach the skin that covers it, and it rea- 
 dily divides inte two parts; these are called lobes, 
