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.