112 THE LIFE OF A TREE. 
been purely carbon, hydrogen, nitrogen, and oxy- 
gen, it ought to have done, leaving nothing behind? 
The same experiment, if we can call so trifling an 
observation by so dignified a title, is made on the 
large scale in many a clearing, or spot redeemed 
from the forest in America. The settlers here 
are overwhelmed with the ocean of wood, which 
surrounds them, and effectually puts a stop to 
the pursuits of agriculture; and they have no 
resource but to cut down tree after tree and burn 
them. What a grievous waste! will be exclaimed 
by those who know the value of fire-wood, in our 
less densely wooded country. But not entirely 
so; the ashes are carefully collected, and are 
melted down, and are then found to contain very 
large quantities of the alkali called potash. This 
is then sent to market, and fetches a very fair 
price. We will mention another fact of a some- 
what similar kind. In many parts of Wales a 
species of fern grows wild in great numbers, and 
beyond serving as litter for horses, or as thatching 
for the cottager’s roof in the place of straw, 
might be looked upon as a very useless plant. 
The cottagers, however, estimate its value very 
differently, and collecting it together in heaps, 
