ON MANURES. 81 



becomes more evenly mixed, and more prompt in its effects 

 upon the land; and when laid upon it in its hot state, it not 

 only occasions the destruction of weeds, but powerfully stimu- 

 lates the action of manure. An idea, indeed, generally pre- 

 vails, in consequence of burning being the mode usually 

 resorted to in the employment of lime, that calcination is 

 necessary to render it lit for use as manure, but this, as we 

 have already remarked, is a mere mistake. 



One very strong reason for applying it instantly is, that, if 

 spread immediately after being turned, and while yet in a 

 powdery and caustic state, a smaller quantity may sutRce to 

 cover the whole surface of the ground, and to come into con- 

 tact with more minute particles of the soil; whereas, if suf- 

 fered to lie for any length of time exposed to the atmosphere, 

 it imbibes so much moisture, that it runs into clods, and can 

 never again be so equally divided into small parts, wherefore 

 a much larger quantity is required to produce the same imme- 

 diate effect. It is in this state, also, that it acts the most 

 powerfully upon all organic matter which may be already 

 lying undecomposed within the soil — insects, the fibres and 

 roots of obnoxious plants, and the seeds of weeds, which it dis- 

 solves and transforms into mould. It is also more efficacious 

 than effete lime in its influence upon what is called sour land, 

 though simple chalk, if applied in large quantities, will correct 

 the evil. Neither is it improbable that, during its process of 

 slaking, the heat which it generates by the absorption of mois- 

 ture causes it to swell in a manner which the tenacity of the 

 soil cannot resist: thus producing fermentation, it not only 

 eventually makes the land mellow, but renders matter which 

 was comparatively inert, nutritive, and is probably more bene- 

 ficial to land containing much woody fibre, or animal fibrous 

 matter, than any calcareous substance in its natural state.* 

 If, therefore, quicklime really possesses superior qualities as a 

 manure, it seems only fair to infer that, the greater the strength 

 and vigor of such properties, the more assuredly will they 

 effect its purpose when in that state, than after it has been 

 rendered effete. 



* In its first effect, burnt lime decomposes animal matter, and seems to 

 accelerate its progress to a capacity of affording nutriment to vegetables : 

 gradually, however, the lime is neutralized by carbonic acid, and converted 

 into a substance analogous to chalk : but in this case it more perfectly 

 mixes with the other ingredients of the soil, and is more pervadingly dif- 

 fused, more finely divided, than mere chalk artificially applied.— Sir Hum- 

 phry Davy, Elem. of Agric. Chem., lect. vii. 



