Having thus difcovered in Spain a perfeX fixed alkali
in the earth, I purfued my oblervatioris on other falts,
and vegetable produXions, and after many refleXions
and experiments, I difcovered that fimilar fixed alkalies,
many oils, and neutral falts", proceed from different
combinations of the air, earth, and water, with fuch
matters as the air conveys in a diffolved Hate, and that
thefe three elements, riling, falling, and meeting, combine
together, and form new bodies in the organs o f
vegetation.
Thofe who are verfed in phyfics, agree, that all the
fubftances of the very globe we inhabit, confift o f the
combinations o f fire, water, earth, and air; why then
deny them the power of combining, in the living organs
o f plants? when we fo often perceive in them, the faculty
o f changing, and transforming produXions in the kingdom
of nature. In proof o f it, we find that many cruci-
formed plants give by analyfis, the fame volatile alkali
as animals, notwithftanding that their tubes are fimilar to
the eye, with thofe that give acids.
Some plants have their roots fo fmall, and yet their
branches, leaves and fruit fo ponderous, that it appears
impoffible, fo inconfiderable a root ihould draw fufficient
nurture out o f the earth for fuch various purpofes. It
fcems therefore, that the ambient air, containing many
diffolved
diffolved bodies, penetrates into the plants, and combines
in the vegetative tubes, forming thofe fubftances
difcovered by analyfation.
I have frequently feen water melons in Spain weigh
from, twenty to thirty pounds, with a ftem o f only two
or three ounces, fo great was the increafe o f the fibrous
and tubulous fubftance o f thofe plants, owing to the
watery particles they imbibed from the air. It fftould
feem then, that many plants draw their principal fup-
port from the air, water, and a fmall portion o f earth,
combined by the imperceptible labour o f the vegetative
tubes, and veffels o f air, which convert thofe matters into
the produXs we contemplate, and tafte; many plants
producing all thefe effeXs in water only, and we find
that mint, and other odoriferous plants whofe roots grow
in water, and in the air, give the fame fpiritus reXor,
and oils, as thofe that grow in the earth.
Botanifts know very well that thofe aquatic plants that
fpring up from the bottom of waters have with a very trifling
deviation, the fame properties and qualities in the
frozen regions, as in fultry and parching climates, and,
that their acrimony, caufticity, infipidity, and coolnefs,
are invariable.
The experiments made by Van Helmont on the willow
tree, making it grow in water, and a fmall portion of dried
E 2 earth.