On Maiden, or Virgin, Soil. 399 



with organic matter in the form of soil, and that the further 

 disintegration of the rock proceeds every time the soil is dug and 

 pulverised, and exposed to the action of the air, we may also 

 infer from observation, when we find the soil by long cultivation 

 dissolving into a powdery incoherent mass.* We thus see the 

 cause why long continued cultivation injures the mechanical 

 texture of the soil, by destroying the molecular attraction of its 

 particles. When a finely raked surface has been exposed to the 

 weather a few weeks, by the missing of a crop, the old surface 

 will not raise a new crop so vigorous, to sow it as it stands, even 

 though cuffed an inch deep, as if pointed and raked anew, and 

 a fresh surface brought up : a proof of the action of the air 

 during that period. 



The cause why resting of the soil, or trenching down the 

 surface, has a tendency to restore its texture is, that pressure 

 and consolidation have a tendency to unite the particles of earth 

 again into stone. Professor Playfair long ago demonstrated 

 the truth of this, when contending for the Huttonian theory 

 of geology, which ascribed consolidation and immense pressure 

 as the cause of the formation of rocks, by actually forming 

 a piece of stone in that way. We see also in the deep con- 

 solidated clays which have been long deposited, as of the Lon- 

 don basin, &c, that in some places, where exposed, they have 

 been found to have become consolidated into stone before the 

 exposure, by the pressure of the superincumbent strata. This 

 tendency to unite again into the form of stone, in the disinte- 

 grated particles of the rock which form the soil, causes them to 

 unite more firmly together when pressed and consolidated, 

 being freed from the action of the air, and pressed together 

 when at rest ; the tendency to unite, though far short of that 

 which would form stone, has yet the effect of causing the par- 

 ticles to adhere uniformly together, and not to dissolve so easily 

 into a mass of loose incoherent powder, as before observed. 



When we consider the necessity of keeping the soil in a 

 proper mechanical condition, we need not wonder at the good 

 effects produced by mending this condition. The coai'se grains 

 of sand are necessary in a certain proportion to keep the par- 

 ticles of alumina from adhering too closely ; and, when the soil 

 is of a rather adhesive clayey nature, immense effects have 



* That it yields alkalies by disintegration, and concerning the nature of alka- 

 lies, of both of which Mr.Wighton pleads ignorance, any of the recent manuals 

 of geology and chemistry, which may be had at very little expense, will furnish 

 information. A tithe of the labour bestowed by him on the subject of bees, 

 to such good purpose, would give him a fund of information on these subjects ; 

 which, in men filling such important stations, from their opportunities of 

 observation in their every-day practice, enabling them to discover how pre- 

 sent received theories are inconsistent with practical results, would be of 

 immense benefit. 



