¢ mw) 
sub-soil be not charged with oily and animal matter, 
will be more injurious than useful. 
But, besides the consideration of getting so little, ) 
and that little of such equivocal character and use, 
what do we lose by the process! If we approach 
these little kilns, we find them emitting a black 
smoke, which cannot be entirely consumed: Our 
eyes and noses are assailed by some stimulating and 
ammoniacal matter, which is fast escaping, and which 
so far alters the atmospheric air in the neighborhood, 
as to render it difficult of respiration. Need we 
add, that this is the animal, oily and gaseous matter 
essential to the vegetable, and highly important to 
vegetation? It may be, that the ashes obtained may 
give one or two good crops of turnips ; but even the 
advocates of this practice admit, that “ it ruins the 
land for an age ; and hence it is that in England, 
tenants are restrained from paring and burning, es- 
pecially towards the close of their leases.”(1)_ 
Clay burning is a different operation, and made 
with different views ; not for the production of ashes 
or salts, which may operate chemically, but merely 
(by the application of heat) to alter the texture of 
the soil; to give to it an artificial division and po- 
rosity ; to render what was cold warm, and what 
was wet dry; what was compact granular. Buta 
sinall degree of heat will not produce these effects; 
for unlike the stems and roots of plants, clay is not 
itself combustible ; and to bring it to the brick state, 
the heat applied must be long, continued and great: 
(1) See Cobhett; part second, p. 168, Year's residencein the WS.” 
