124 HORTUS GRAMINEUS WOBURNENSIS. 



It may be said, that as the want of a due proportion of finely 

 divided earthy ingredient is all that is needed to render these soils 

 equal to the best, the clay, chalk, &c. may be applied in sufficient 

 quantity to effect so desirable an end. In the instance of the rich 

 siliceous soil, and all others of a similar nature, this may be effected 

 under ordinary circumstances with little trouble, and at a moderate 

 expense. But we shall find, on referring to the details which shew 

 the composition of the poor siliceous sandy soil (No. I.), for 

 instance, that the expense of applying so large a quantity of 

 ingredients as that soil requires, would exceed the value of the 

 improvement under ordinary circumstances. A chemical examin- 

 ation of these soils affords the clearest evidence to determine 

 what degree of improvement they are susceptible of receiving, to 

 be of the most advantage, whether for the production of the supe- 

 rior perennial grasses, or for annual crops only. 



The composition of the tenacious clay (No. VIII.), shews that 

 it contains all the ingredients necessary for the improvement of 

 the poor siliceous soil (No. I.), except that of decomposing vege- 

 table and animal matter, which is to be supplied by manure. 



A cubic inch of that clay, when newly dug, weighs 700.8 grains ; 

 when freed from moisture, 584 grains. Suppose one cubic inch of 

 clay to be applied to 29 cubic inches of the soil, it would reduce 

 the proportion of sand, and increase the proportion of finely divided 

 earthy matter, of its former composition, in the following degree : 



1 cubic inch of poor siliceous sandy soil, as before stated, 



consists of 



Fine sand - - 434.875 grains. 



Decomposing vegetable matter 7.35 



Carbonate of lime, or chalk 4.9 



Silica, or the earth of flints 13.475 



Alumina, or the matter of clay - 7.35 



Oxide of iron 3.675 

 Soluble vegetable and saline matters 36.75 

 Carbonate of magnesia 



1 cubic inch of the tenacious clay, added to 29 of the soil, alters 



the proportions in one cubic inch, to, 

 Fine sand - - 428.1171 grains. 



Decomposing vegetable matter - 7.5916 

 Carbonate of lime, or chalk 5.956 



Silica .... 18.4278 



