177 
Here the quantity of fixed water, yielded by the beans which 
had vegetated in soil, was more than three times greater 
than what was obtained from those which had been fed solely 
by distilled water. 
The same philosopher examined the ashes of various plants 
growing on a granitic, and on a calcareous soil. The plants 
which grew on the granitic soil contained a considerable pro- 
portion of silica and metallic oxides ; those which grew in the 
calcareous, little or none of these bodies, but a greater propor- 
tion of calcareous earth than the granitic plants. 
'I’lius it cannot be doubted, that the proportion of earthy 
matter contained in plants is considerably influenced by the 
nature of the soil on which they grow ; but whether plants de- 
rive the whole of these fixed principles from the soil, or whether 
they are capable of forming them to a certain extent by the 
unknown powers of vegetation are ({uestions not yet finally 
decided. 
180 Saline MATTER i\ Plants. “ Besides earths, plants always 
contain a portion of saline matter. Those that grow at a dis- 
tance from the sea contain potash, while sea-plants contain 
soda and common salt. Phosphate of lime is a constant ingre- 
dient, and phosphate of potash a very common one. Some 
plants contain ])eculiar salts. Thus nitrate of soda is usually 
present in barley, nitrate of potash in nettles and the sun- 
flower, &c. It appears from the experiments that have been 
made, that peculiar salts promote the vegetation of peculiar 
plants. Sea plants require common salt, and languish in soils 
wliere it is not to be found. Borage, nettles, and pellitory, 
thrive only in soils which contain nitrate of lime or potash : 
gypsum promotes the vegetation of lucern and clover. 
Salts then are not inactive; and when properly applied, they 
promote the growth of vegetables. In these cases they appear 
to be absorbed by the plants which they invigorate. Duhamel 
found tliat sea plants made little progress in soils which con- 
tain no common salt. Bullion made seeds of sun flower to 
grow in a sandy soil, containing no trace of nitre. On examin- 
ing the plants, no nitrate of potash could be detected in them, 
but the salt made its appearance as usual when the plants were 
watered with a weak nitrous solution. From the experiments 
of Saussure, we learn that plants absorb saline solutions in very 
139 ACCTABICU. 
