240 ESSAYS AND OBSERVATIONS 



know, loft. What we call a vegetable 

 mould, is an earth in which there is ftore 

 of fuch parts of vegetables lodged, the ma- 

 trix in which they lie, being a fine but bar- 

 ren fand. As long as there is a fufficient 

 ftock of fuch particles in any earth, that 

 ground is fruitful j but when this is exhauft- 

 ed, which happens fooner or later, from the 

 quantity of vegetables nouriftied by it, and 

 carried off for the ufes of life, it becomes 

 barren. The only remedy, when no better 

 can be had, is to allow it to reft, until it re- 

 ceives a new recruit from the air, in which 

 are perpetually floating, and falling down up- 

 on the earth, particles of all kinds, proper 

 for the nourifliment of plants. But as this 

 is a tedious way of recovering the fertility 

 of ground, the better and more expeditious 

 one, is by laying dung upon it, which being 

 wholly made up of putrefied vegetables, or 

 animals, equally proper for nouriftiing plants, 

 the parts, of which both are compofed, be- 

 ing the fame, and the tranfition from the one 

 to the other eafy j the ground by this new 

 acquifition becomes again fertile. Every ve- 

 getable then whofe parts are fet loofe, by 

 that laft fermentation of nature, putrefadion, 



affords 



