USEFUL APPLICATIONS TO PRACTICE. 211 



or as manure by man, beyond the present wants of the soil, is 

 only of value so far as being there ready for any future increased 

 demand of the soil, and so may supersede the necessity of another 

 supply being required as soon. Therefore, however active may be 

 the solvent power of water, and however rapid the consequent 

 waste of the excess of lime in the soil, the operation can detract 

 nothing from any manuring value, or quantity of the lime, pre- 

 viously and then existing. 



The statements and reasoning of Prof. Johnston brought to prove 

 the waste and final disappearance of all lime used as manure, how- 

 ever inconclusive for his object, furnish important truths for 

 practical use. We may thence deduce additional reasons for the 

 impropriety of laying on at once too much marl or lime for the then 

 wants of the soil; and also of the usual unequal diffusion, which 

 serves to make even a light dressing excessive in many spots, while 

 entirely wanting in others. Not only, as I had before urged, is all 

 such excess of quantity, whether general or partial, a waste of 

 labour, a conversion of active to dead capital, and the causing 

 danger of actual injury to crops but further, such excess of lime, 

 or carbonate of lime, is subject to more or less waste, by solution 

 and removal, so long as it remains superfluous, and not required 

 for immediate use by either the soil or growing plants. It is such 

 excess as this in soils, that furnished all the wasted lime found by 

 chemists in the waters discharged by drainage from limed lands. 

 Still more extensive natural operations pf the same kind, and 

 stronger proofs, are to be seen in all lime-stone and highly cal- 

 careous regions. The rain-water filtrating through such rocks and 

 soils, becomes universally and highly charged with lime ; of which 

 a large portion is removed and lost to the place of its origin, by 

 flowing off into sources of springs and streams. Another portion, 

 by filtration, may sink deep into the earth. In limestone and chalk 

 regions, indications of the quantity of lime dissolved by rain-water, 

 from the rocks and soil, and carried off by springs, may be observed 

 not only in the lime-impregnation of spring-water, but also in the 

 deposition of travertine, or calcareous tufa, at the rapids of streams ; 

 and of the loss by filtration in the stalactite deposits in every 

 cavern of the earth. 



There remains to state one other manner of the loss of lime in 

 soil, which is mentioned by Prof. Johnston, and also other authors, 

 as being a common, if not a general result in England. This loss 

 is caused by the tendency of lime, which has been applied, to sink 

 below the upper soil. " It has long been familiar to practical men," 

 says Johnston, " that when grass lands, which have been limed on 

 the sward, are after a time broken up, a white layer or band of 

 lime is seen at a greater or less depth beneath the surface, but 

 lodging generally, where it has attained its greatest depth between 



