30 MANURING THE SOIL. [chap. n. 
escape of the water* and it be continually 
enriched with manure* it will be changed 
in time into the black slimy substance that 
has been already described. 
Surface-soil is called peat-earth when it 
is composed of decayed vegetable matter* 
without any mixture of animal manure; and* 
as this excess of vegetable matter could 
neither be produced nor decayed* without 
abundance of stagnant moisture* this kind 
of earth is almost always found on a clayey 
sub-soil* which prevents the water which falls 
upon it from escaping. Peat-earth has a 
spongy* elastic feeling when trodden upon* 
arising from the quantity of water that it 
holds* and it can only be rendered fit for 
cultivation by draining. In its elastic state 
it is what is called in Scotland a moss* and 
in England a peat-bog. Should the water* 
instead of being afforded a vent by drainage* 
be suffered to accumulate for many years* 
till it completely saturates the peat* the soil 
becomes what is called a morass* or quag¬ 
mire ; and it can no longer be trodden on* as 
it will engulf any substance resting upon it. 
A still further accumulation of water will* 
