104 QUICK-LIME AS MANURE. 



which takes place between these bodies forms different compounds, 

 which are always less valuable than the putrid or soluble matters 

 were, before being acted on by the lime.* 



This theory will direct us to expect profit from applying caustic 

 lime to all soils containing much unrotted and inert vegetable 

 matter, as our acid wood-land when first cleared, and perhaps worn 

 fields, covered with broomgrass ; and to avoid the application of 

 lime, or (what is the same thing) to destroy previously its caustic 

 quality by exposure to the air, for all good soils containing soluble 

 vegetable or animal matters, and on all poor soils deficient in inert, 

 as well as in active nourishment for plants. The warmth of our 

 climate so much aids the fermentation of all putreseent matters in 

 soils, that it can seldom be required to hasten it by artificial means. 

 To check its rapidity is much more necessary, to avoid the waste 

 of manures in our lands. But in England, and still more in Scot- 

 land, the case is very different. There, the coldness and moisture 

 of the climate greatly retard the fermentation of the vegetable 

 matter that falls on the land ; so much so that, in certain situa- 

 tions, the most favourable to such results, the vegetable cover is 

 increased by the deposit of every successive year, and forms those 

 vegetable soils which are called moor, peat, and boy lands. Vege- 

 table matter abounds in these soils, and sometimes it even forms 

 the greater bulk for many feet in depth j but it is inert, insoluble, 

 and useless, and the soil is unable to bring any useful crop, though 

 containing vegetable matter in such great excess. Many millions 

 of acres in Britain are of the different grades of peat soils, of 

 which almost none exist in the eastern half of Virginia. Upon 

 this ground of the difference of climate, and its effects on ferment- 

 ation, I deduce the opinion that caustic lime would be serviceable 

 much more generally in Britain than here ; and indeed that there 

 are very few cases in which the caustic quality would not do our 

 arable lands more harm than good. This is no contradiction to 

 tlje great improvements which have been made on many farms by 

 applying lime ; for its caustic quality was seldom allowed to act at 

 all. Lime is continually changing to the carbonate of lime ; and, 

 in practice, no exact line of separation can be drawn between the 

 transient effects of the one, and the later, but durable improve- 

 ment from the other. Lime powerfully attracts the carbonic acid 

 of which it was deprived by heat, and that acid is universally dif- 

 fused through the atmosphere (though in a very small proportion), 

 and is produced by every decomposing putreseent substance. Con- 

 sequently, caustic lime, when on land, is continually absorbing 

 and combining with this acid \ and, with more or less rapidity, 

 according to the manner of its application, is returning to its for- 



* Davy's Agr. Chem. Lect. viu 



