for scientific principles. Influence of the atmosphere. Of Saline
and Earthy matters of the soil.


LETTER XII

SCIENCE AND ART OF AGRICULTURE. NECESSITY OF CHEMISTRY. Rationale of
agricultural processes. Washing for gold.


LETTER XIII

ILLUSTRATION OF THE NECESSITY OF CHEMISTRY TO ADVANCE AND PERFECT
AGRICULTURE. Manner in which FALLOW ameliorates the soil. Uses of
Lime. Effects of Burning. Of Marl.


LETTER XIV

NATURE AND EFFECTS OF MANURES. Animal bodies subject to constant
waste. Parts separating--exuviae--waste vegetable matters--together
contain all the elements of the soil and of food. Various value of
excrements of different animals as manure.


LETTER XV

SOURCE OF THE CARBON AND NITROGEN OF PLANTS. Produce of Carbon in
Forests and Meadows supplied only with mineral aliments prove it to
be from the atmosphere. Relations between Mineral constituents, and