QUICK-LIME SOON CARBONATED. 105 



mer state of mild calcareous earth. If .spread as a top-dressing 

 on grass lands or on ploughed land, and superficially mixed with 

 the soil by harrowing or used in composts with fermenting vege- 

 table matter the lime is probably completely carbonated, before 

 its causticity can act on the soil. In no case can lime, applied 

 properly as manure, long remain caustic in the soil. Thus most 

 applications of lime are, in effect, and even from the beginning of 

 the manuring action, simply applications of calcareous earth ; but 

 acting with greater energy and power at first, in proportion to the 

 quantity, because more finely divided, and more equally distributed. 



[Whether lime, or carbonate of lime, or calcareous earth, may 

 be the term used in reference to any such manure used, or recom- 

 mended, the general, most important, and all effects other than 

 some of the earliest and least certain to occur, are the same in 

 practice of all. The operation in every case is that of calxing. In 

 presenting the theory, and in reasoning, and instruction, it is im- 

 portant to maintain the precise line of separation and distinction 

 between the artificial product, quick or caustic lime, and the 

 naturally existing calcareous earth, or carbonate of lime. But in 

 practical effects they are the same, excepting those only which 

 may be due to the different early conditions of the different sub- 

 stances. Therefore, (always allowing for those early and transient 

 and minor differences), whatever I may say of the operation of 

 calcareous earth as manure, would as well be produced by the pro- 

 per use of lime ; and whatever other writers on lime as manure 

 have correctly stated, even though perhaps designed by them to be 

 confined to quick-lime, would, as to all abiding and important 

 effects and operations, apply as well to mild and naturally existing 

 calcareous earth, in any of its various forms. 



Further even when the first chemical characters of both caustic 

 lime and carbonate of lime have been altered in the soil, and they 

 may have become changed to other salts of lime, by combining 

 with different acids of soils, still, judging from all experienced and 

 abiding effects, the general and beneficial operations of the original 

 manures still continue. The only known exception is, and which 

 is abundantly obvious, that the power to neutralize acids has then 

 been fully used, and cannot again be exercised by the same lime 

 on any subsequently produced acids. 1849.]* 



{_* Recent Confirmation. Johnston says " The effects of pure lime upon 

 the land, and upon vegetation, are ultimately the same, whether it be laid on 



in a state of hydrate [or newly slaked], or of carbonate." 



" In general, however, the chemical action of the marls and calcareous 

 sands is precisely the same in kind as that of lime in the burne^ and slaked 

 state, and so far the effects which we have already seen to be produced by 

 marls, represent also the general effects of lime in any form." Lectures, 

 p. 390. And further "You may safely proceed on the principle that the 

 lime in the marls, &c., will ultimately produce precisely the same effects 



