HOHTUS GRAMINEUS WOBURNENSrS. 77 



under circumstances as similar as possible to that of plough- 

 ing it five inches deep, in the usual manner of breaking up 

 pasture land. 



The nature of the soil was now ascertained, by taking up 

 a portion of it to the full depth, only rejecting the green 

 living vegetable parts of the turf. 



400 grains, freed from moisture and the plants of grass, 

 consisted of — 



Calcareous and siliceous sand, of different 



degrees of fineness 102 grains. 



Decomposing vegetable matter, and par- 

 ticles of roots ,. 55 



Carbonate of lime, or chalk 160 



Silica, or earth of flint 50 



Alumina, or pure matter of clay 25 



Oxide of iron 4 



Soluble vegetable matter, and gypsum.... 4 



The soil was then cropped for five seasons alternately, 

 with, first, oats; second, potatoes; third, wheat; fourth, 

 carrots : and fifth, wheat — to the end that it miaht suffer as 

 much as could possibly happen, under ordinary circum- 

 stances, by an impoverishing or injudicious rotation of annual 

 crops. Every trace of the turf was by this time entirely lost 

 in the general mass of the soil, which v/as now examined, to 

 ascertain what change it had undergone by these crops. 

 It appeared to consist of — 



Calcareous and siliceous sand, nearly as 



before 100 grains. 



Decomposing vegetable matter, destructi- 

 ble by fire 48 



Carbonate of lime, or chalk, nearly as 



before 159 



Silica, or earth of flint 57 



Alumina, or pure matter of clay 26 



Oxide of iron 5 



Soluble vegetable and saline matter 3 



The above details show, that very little, if any change. 



