i8 A TREATISE OF 



perfons, I fhall not contend with them, but 

 leave them to their own opinions ; only 

 defire, that they will inform me of what 

 fervice the frefh earth is to trees, any far- 

 ther than by the falts therein contained, 

 which it has at various times received from 

 the excrements of cattle long pafturing 

 upon its furface, the fahne particles of 

 which, defcending to the roots of the grafs, 

 render the earth more fertile, and for that 

 reafon is frequently made choice of for 

 fruit-trees. 



It has been evidently proved by Dr. Keil, 

 that the growth of a tree very little leffens 

 the weight of the earth in which it grew; 

 v/hich difference of weight is purely owing 

 to the greater quantity of falts contained 

 in the earth when the tree was planted, 

 than at the time of taking it up. 



For admit the tree be taken up and 

 burnt to charcoal (in doing which a great 

 part of its watery particles evaporate, and 

 fome of the nneft faline parts) and the 

 cliarcoal buriu to afhes, in the afhes there 

 Will be contained a large quantity of falts, 

 which may be made apparent by pourin-g 

 water upon ihcrn, araining it fr4)m them^. 



and 



