ELEMENTS OF AGRICULTURE. 
3d 
QUESTIONS. 
1. Whence come the organic substances found in the soil? 
2. What mineral elements are found in the earth in the greatest quantity ? 
3. Which are those more rarely found? 
4. In which case is the soil entirely barren ? 
5. What is a light soil ? 
6. What is a stiff soil 1 
7. Which are the most difficult lands to cultivate ? 
8. Into how many classes may soils be divided ? 
9. What is understood by calcareous soils ? 
10. What by loamy land ? 
11. WhiOh is the best to cultivate ? 
12. Why is it particularly useful to be familiar with the properties of tha 
eonstituents of a soil ? 
LESSON III. 
SILEX, OR SILICA. 
16. Silex, or silicious sand, is composed of two ele¬ 
ments— oxygen, and a metal called silicium. This metal 
is found in the common flint, in almost a pure state. It is 
not soluble in water, and can only be decomposed by fluo¬ 
ric, or phosphoric acid. An earth is recognised to be sili¬ 
cious when, mixed with water, it will not work into a 
paste. 
17. Silica is very generally diffused throughout the 
earth. It is met with, in greater or less quantities, in al¬ 
most all soils; and when not in excess, so far from being 
injurious, it is beneficial to the soil, by rendering it lighter, 
easier to work, and more favorable to vegetation. 
18. But when sand predominates in a soil, it communi¬ 
cates defects that diminish its value. Crops upon it are 
exposed to suffer from drought, because silica does not 
lime is an ameliorator, by the property which it possesses of rendering stiff 
lands of easier cultivation, and giving more compactness to lands that are 
too light 
