112 HOW CROPS GROW. 
In the subjoined table, the names of the 12 elements of 
the ash of plants are given, and they are grouped under 
two heads, the non-metals and the metals, by reason of an 
important distinction in their chemical nature. 
ELEMENTS OF THE ASH OF PLANTS. 
Non-Metals. Metals. 
Oxygen Potassium 
Carbon Sodium 
Sulphur Calcium 
Phosphorus Magnesium 
Silicon Tron 
Chlorine Manganese 
If to the above be added 
Hydrogen and Nitrogen 
the list includes all the elementary substances that belong 
to agricultural vegetation. 
Hydrogen is never an ingredient of the perfectly burned 
and dry ash of any plant. 
Nitrogen may remain in the ash under certain conditions 
in the form of a Cyanide, (compound of Carbon and Ni- 
trogen,) as will be noticed hereafter. 
Besides the above, certain other elements are found, cither occasion- 
ally in common plants, or in some particular kind of vegetation: these 
are Iodine, Bromine, Fluorine, Titanium, Arsenic, Lithium, Rubidium, 
Barium, Aluminum, Zinc, Copper. 
‘We may now complete our study of the Composition 
of the Plant by attending to a description of those ele- 
ments that are peculiar to the ash, and of those compounds 
which may occur in it. 
It will be convenient also to describe in this section 
some substances, which, although not ingredients of the 
ash, may exist in the plant, or are otherwise important to 
be considered. 
The non-metallic elements, which we shall first no- 
tice, though differing more or less widely among them- 
selves, have one point of resemblance, viz., they and their 
compounds with each other have acid. properties, 7. ¢. they 
