234 SOLVENT ACTION OP CALX. 



I. Causing the more rapid decomposition and perfect solubility 

 of vegetable matters, otherwise inert or insoluble. 



II. Enabling either the soil, or the plants growing thereon, to 

 draw from the atmosphere greater supplies of manuring or aliment- 

 ary principles, viz. : 



1. Carbon, to growing plants; 



2. Azote (nitrogen), from the atmosphere, through the instru- 

 mentality of leguminous plants; 



3. Nitric acid, and nitrates, to the soil, and thereby increasing 

 the supplies of azotic principles to growing plants. 



III. Giving to all growing plants a more healthy constitution, 

 and more vigorous vital powers, and thereby more ability to with- 

 stand dangers and injuries of all kinds. 



These several branches of the subject will be discussed in the 

 following pages ; and so far as they admit of separation, in the 

 order stated. 



I. Lime and Carbonate (and other Salts) of Lime render Vege- 

 table and Organic matters more soluble. 



It is a well established chemical action of the fixed alkalies pro- 

 per (potash and soda), on vegetable or other organic matter, to render 

 it more soluble, and thereby more speedily and effectually to reduce 

 insoluble and inert organic manures to the state fit to be taken up 

 by the roots of plants ; and enable them to be more completely 

 consumed as food for plants. It may well be inferred, from the 

 general resemblance of chemical properties, that this solvent action 

 of the alkalies proper must also belong to the alkaline earths, lime 

 and magnesia, even though in combination with carbonic acid 

 That caustic or pure lime exerts this solvent power was stated 

 previously (page 103), when treating of its manuring action. Like 

 effects, as exhibited in the rapid disappearance of leaves, &c., on 

 calcareous and neutral soils, were also stated (page 98), from which 

 effects it might be inferred that this solvent power attended lime in 

 all its ordinary combinations or conditions in soil ; though perhaps 

 then exerting this power more slowly than either caustic lime, or 

 carbonate of potash. These well-known effects on natural soils, 

 and also the quicker and better effects of unrotted putrescent ma- 

 nures when applied to calxed lands, I had ascribed altogether to the 

 indirect action of calcareous earth, in its having neutralized the 

 previously existing acid, which was antiseptic, and prevented or 

 retarded the rotting and solubility of the vegetable matters. But 

 besides this indirect action, there seems good reason to believe that 

 there is also a direct solvent power exerted by salts of lime, similar 

 to that of the alkalies proper, and their salts, or combinations with 

 acids. Rennie and Thaer have expressly extended this known 

 chemical action of the alkalies proper to the alkaline earths, even 



