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264 ESSAYS ann OBSERVATIONS 
the earth. Thus it goes on growing un- 
til it has attained its utmoft perfection: 
After which it gradually decays, dies, and 
at laft rots and putrefies. By putrefacti- 
on, the parts of which the vegetable was 
compofed, viz. its falts, oils, phlegm, and 
éarth, are feparated: Part remains upon 
the ground where the plant falls ; but the 
far greateft part being volatile, flies up 
into the air, from whence it defcends a- 
gain upon the earth and incorporates 
with it. The fame materials ferve to 
nourifh new plants, there being no part 
of them, as we all know, loft. What we 
call a vegetable mould, is an earth in 
which there is ftore of fuch parts of ve- 
getables lodged, the matrix in which they 
lie being a fine but barren fand. As 
long as there is a fufficient ftock of fuch 
particles in any earth, that ground is 
- fruitful; but when this is exhaufted, 
which happens fooner or later, from the 
quantity of vegetables nourifhed by it, 
and carried off for the ufes of life, it be- 
comes barren, The only remedy, when 
ne 
