4d On the Analysis of Soth. 



principallv upon its power of attracting principles bf vcgf- 

 table nourishment from water and the atmosphere*. 



Mr. Tillet, in some eXperinicnts made on the composi- 

 tion of soils at Paris, found that a soil composed of three- 

 eiehths of clayj two-eightiisof river simd, and three-eighths 

 orthe parings of linicstone, was very proper for wheat. 



XIX. Of the Composition of Soils proper for lulhous Roots 

 and for Trees, 



In general, bulbous roots require a soil much more sandy 

 and less absorbent than the grasses. A very good potatoe 

 soil, from Varsel in Cornwall, afforded me ^even-eighths of 

 siliceous sand j and its absorbent p^)wer was so small, that 

 one hundred parts lost only two by drying at 400 Fahren- 

 heit. 



Plants and trees, the roots of which are fibrous and hard, 

 and capable of penetrating deep into the earth, will vegetate 

 to advantage in almost all common soils v.-hich are mode- 

 rately dry, and which do not contain a very great excess of 

 Vegetable matter. 



I found the soil taken from a field at Sheffield-place in 

 Sussex, remarkable for producing flourishing oaks, to con- 

 sist of six parts of sand, and one part of clay and finely di- 

 vided matter. And one hundred parts of the entire soil, 

 submitted to analysis, produced 



XX. Advantages of Improvements made ly changing the 

 Composition of the earthy Parts of Soils. 

 From the great difference of the causes that influence the 

 productiveness of lands, it is obvious that, in the present 

 state of science, no certain system can be devised from their 

 improvement, independent of experiment: but there sire 

 few cases in which the labour of analytical trials will not be 

 amply repaid by the certainty with which they denote the 

 best methods of amelioration ; and this will particularly 



• This soil was sent to me by T. Poole, Esq. of Nether Stowey. It is near 

 the opening of the river Parret into the B.'itish Chanael ; but, 1 am told, is 

 never overflowed. 



happen 



