86 A PRACTICAL TREATISE 



matter which forms part of it, and which may be injurious to 

 vegetation, either harmless or useful; and thus to prepare the 

 soil for the reception and nourishment of seeds and plants: and 

 secondly, to facilitate the decomposition of putrescible matter, so 

 as to furnish food to vegetables during their growth. It has been 

 proved by careful experiment, that the application of lime is tfie 

 only known alterative which, upon poor, weak, and weeping 

 clays, has power to heal the soil. With the assistance of 

 water, it suddenly decomposes all animal and vegetable 

 bodies, and when thus spread upon neglected ground covered 

 with heath and moss, the old turf is decomposed, and a sapo- 

 naceous matter is formed, which sinks into the soil and covers 

 it with sweet herbage. We also know that 'it imparts a 

 certain degree of vigour to some peculiar plants, — as, for 

 instance, sainfoin, the roots of which penetrate far into tlie 

 interstices of chalk, and grcJw luxuriantly, though only covered 

 by a slight coat of inferior soil.* 



It is, however, an error, — though entertained by many 

 farmers, — to suppose that lime in any state comprises fer- 

 tilizing properties within itself: and that, without operating 

 upon the soil, or upon the substances which it contains, it is 

 an enriching manure. It does not possess any fertilizing 

 principle in its own composition : it is merely a calcareous 

 earth combined with fixed air, and holding a medium between 

 sand and clay, which, in some measure, remedies the deficien- 

 cies of both. But though, when alone, unfavourable to the 

 growth of plants, yet experience shows that it is an ingredient 

 in soils which, whether naturally form in »• a component part 

 of their substance, or judiciously mixed with them by the hus- 

 bandman, adds greatly to their fertility, for it has the power 

 of attracting much both from the earth and from the air, which 

 occasions the decomposition of plants; and thus converting 

 them into nutriment, it gives power as to vegetation which, 

 without its operation, would otherwise lie dormant. It also 

 appears to act with great force upon that substance which, 

 being already converted by tlie decomposition of plants into a 

 species of earth, we call mould.\ 



The other causes with which we are acquainted regarding 



* See Naismith's Elements of Ajrrif nlture, p .?34. Timer, Principes Rai- 

 sonnesd'A};rriculture,2iKle edit., tome ii. p. 3S7 ; and Anderson's Essajs, No. 

 vi.. Aphorism iv., in uiiicli it is stated, that calcareous matters act as power- 

 fully \ipon land that is naturally poor, as upon land that is more richly impreg- 

 nated with those substances which tend to produce a luxuriant vegetation. 



t Respecting the formation of mould, see the chapter on soils. 



