The importance of this subject has been alrradr fc[i 

 by some vei}' able cultivators of sconce ; many useful 

 facts and observations with reirm-d to it liave been fur- 

 nished by Mr. Young ; it has b-^en examined by Lord 

 Dundonald, in his treatise on the conr.exion of Chymis^ 

 try with Agriculture, and by Mr. Kirvvan in his excel- 

 Jent essay on M nures ; but the enquiry is sti'l far from 

 beifg exhausted, and new methods of elucidating it are 

 almost continually offered, in consequence of the rapid 

 p >gress of ("hymical discovery. 



in <he following pages I shall have the honour of hiy- 

 ini,';b» lore the Board, an account of those methods ofanav 

 Ivsing soils, wh eh appear most precise and smiple, ^nd 

 niosf likely to he useful to the practical farmer ; ihey are 

 fou ided partly upon the labours of the gentlemen whose 

 nunes have been just mentioned, and partly npon soms 

 later improvements. 



II if the, Si(h stances found in Soils. 



The substa -CCS which are found in soils, are certaia 

 mixtures or combinations of some of the primitive earths^ 

 animal and vegetable matter in a decomposing s«ate, 

 certain sah'ne compounds, and the oxide of iron. These 

 bodies always retain water, and exist in very different 

 proportions in different lands ; and the end of analytical 

 experiments is the detection of their quantities and 

 mode of un;on. 



The earths found in common soils, are principally s'u 

 lex, or the earth of flints, alumine, or the pure matter of 

 cl iy, lime, or calcareous earth, and magnesia. 



Silex, or the earth of flints, when perfectly pure, ap- 

 pears in the form of a white powder, which is incombus- 

 tible, infusible, insoluble in water, and not acted upon 

 by common acids ; it is the substance which constitutes 

 th;^ principal i-art of rock chrystal ; it composes a consi- 

 derable part of hard gravelly soils, of hard sandy soils, 

 ani of hard stony lands. 



ALumine, or pure clay, in its perfect state, is white like 

 ^ilex ; it adheres strongly to (he tongue, is incombusti. 

 t?k"> insoluble in water, but s©iuWe in acids, and ra h-Yc4 



