THE SOIL OF THE FARM. 397 



LIME is widely distributed, and occurs in vast quantities. The chalk 

 hills which sweep through England are almost pure lime. The Lower 

 Oolite consists largely of lime, and the rnagnesian and mountain lime- 

 stones occupy large areas of several counties. Lime is also found in the 

 form of marls and marbles in many other geological formations, so that it 

 is available for agricultural purposes in nearly all localities. It i- em- 

 ployed as a manure in the forms of chalk, marl, and burnt lime, ani 

 application and uses will occupy us when we consider the subject of man- 

 ures. At present it appears before us as a constituent part of all fertile 

 soils, and its wide distribution is illustrated by the fact that it invariably 

 occurs in such soils in greater or less proportions. Although spoken of 

 as " lime " by the farmer, it is more correctly described as calcium car- 

 bonate (carbonate of lime). The carbon dioxide is readily displaced, and 

 Hies off with brisk effervesence when any stronger acid is applied. Pur. 

 calcium carbonate is found in nature in the forms of Iceland spar, white 

 marble, and chalk. When exposed to a red heat it parts with its carbon 

 dioxide and water, and when cool it is found to be porous in texture, and 

 to exhibit an avidity for moisture and carbon dioxide, which renders it 

 caustic. It reabsorbs the water, and to a limited extent the carbon diox- 

 ide from the atmosphere, and as it does so " slakes " or " falls " into a mild 

 powdery mass. If water is poured over the calcined lime, the slaking is- 

 more rapid, and accompanied by the evolution of much sensible heat. T 

 characteristic colour of lime is white that of the Magnesian, such as that 

 at Guelph, Ontario, having a yellow tinge. It is intermediate between 

 Niind and clay in tenacity and in its power of holding water. 



Lim: is an important constituent of all fertile soils. It is in itself a 

 plant food, and a valuable manure. It exerts a strong effect upon decay- 

 ing v^-tabli- matter by accelerating its resolution into carbon dioxide, 

 ammonia, and water; it also combines with vegetable acids, and form< 

 with tli-iii neutral linn -> alts, no longer injurious to vegetation. It \>\ 

 an important part towards tin- mineral matter of the soil, by decoin{><> 

 the silicates and setting free their alkalies. Lime acts nurhanically U 



roving th.- texture <>f clay BOils, and l.-in-- of intcriMi'dial-' tenacity 



is also abli- to confer a higher degree of consistency iij>n light soils. Likr 



. linn- ow.-s its agricultural valu- in a u r reat degree to its impiiri;' 

 in linn- ' nanir inijli^. contains fr,.i 



MM carbonate, and about, or a ' pot ci-nt. of calcium 



TIi'- limestones which form tin- ('lialk.and tin- formation* of 

 mountain ai chi.-ily composed of the latt 



bi it associated with it there jliosj.l : oal- 



