chap. II,] MANURES. 33 
of the sun. Rain also penetrates into it 
very slowly, and not to any great depth. 
Chalk mixed with sand forms a kind of cal¬ 
careous loam admirably adapted for growing 
vegetables; and chalky soils are peculiarly 
susceptible of improvement from manure. 
Manures .-—The kinds of manure generally 
used in gardens are horse or cow dung, and 
decayed vegetable matters; the manure in 
both cases being suffered to lie in a heap to 
rot before it is spread on the ground, in 
order that its component parts may be de¬ 
composed by fermentation, and thus brought 
into a fit state to afford food to the plants. 
Old hot-beds or mushroom beds are thus 
well adapted for manuring a garden; and 
when fresh stable-du^g is employed for that 
purpose, it is generally thrown into a heap, 
and turned over several times till the fer¬ 
mentation has abated, before it is dug into 
the ground. As, however, a great quantity 
of carbonic acid gas is evolved and escapes 
during the process of fermentation, and as it 
seems a great pity that so much of the nu¬ 
tritious properties of the manure should be 
lost, it is now customary to cover the dung- 
D 
