CHAP. iv. CHALK AND LIME. 1025 



insinuates itself, and thus opens the clay to the action of the sun, air, 

 rain, and frost, so that its too cohesive particles become loose, and it 

 is reduced to a state of pulverisation. Chalk may also be usefully 

 employed on sandy land, which it often renders sufficiently compact 

 for the purposes of vegetation. In laying chalk on grass iands, care 

 should be taken to reduce the lumps, for it may be long before the 

 weather will pulverise them sufficiently to enable them to become 

 incorporated with the soil ; and if left on the ground they will impede 

 the scythe. The quantity per acre varies from 10 to 30 tons according 

 to the nature of the soil to which it is applied, rich land not requiring 

 so large a quantity as poor or light lands do. The effects of such a 

 dressing are by no means immediate, one or two years often elapsing 

 before they become apparent, but on soils to which it is suited it is a 

 very permanent amelioration. Lime is more generally applied than 

 chalk to grass and pasture lands, but when employed in considerable 

 quantities, and pulverised, beneficial effects have been experienced from 

 the latter, especially where the land is light and sandy. 



LIME is extensively used for manuring lands ; it is best applied in 

 the "slaked" condition. Chalk, to which reference has just been 

 made, as well as all other forms of limestone, consists of the carbonate 

 of lime. By heating this to a sufficient extent, as in a lime-kiln, the 

 carbonic acid gas is driven off, and the material left behind is called 

 quicklime or caustic lime. This latter, mixed with water a process 

 attended by the production of much heat, forms slaked lime. Con- 

 fusion often arises through the indifferent use of the term "lime " as 

 denoting either quicklime, slaked lime, or carbonate of lime (chalk, 

 limestone). - 



When quicklime is applied to land it ought to be spread as 

 expeditiously as possible, in order that it may be duly slaked and 

 blended with the soil. In this form it is more especially suited for 

 boggy, peaty, heathy, and mountainous soils ; for waste lands which 

 are over-run with fern, broom, furze, rushes, or other coarse vegetable 

 growth that has induced an acidity unfavourable to vegetation ; and 

 for tenacious clays, which, being thereby loosened and rendered 

 friable, are more easily worked, and more readily penetrated by the 

 root-fibres of plants. On old sheep-walks and commons, and on low, 

 rich, and drained meadows, which have formerly been marshes, and 

 which contain a very considerable quantity of vegetable matter, it is 

 also of singular benefit ; for the lime, in all these cases, entering into 

 chemical combinations in the soil, accelerates putrefaction, as well as 

 nitrification of the organic matter of the soil, neutralizes organic acids, 

 and generally improves both the chemical and physical condition of 

 the land. 



The quantity of lime usually spread on land varies considerably ; 

 much depends upon the quality of the lime, and still more upon the 

 nature of the soil to which it is applied. The general allowance, in 

 the estimation of experienced farmers, used to be from 2 to 8 tons 

 an acre, particularly where the land has for a long time been in a 



3u 



