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lands, yet it shows its great value to the ag;riculfure of the 

 Sonlh so much more forcibly than anything I can say in 

 advocating its claims, that I take the liberty of quoting the 

 following paragraphs entire, and with them will close my 

 letter, already too long : 



" At the risk of uttering what may be de^ed trite or 

 superfluous to many, I beg leave to state concisely the fun- 

 damental laws, as I conceive them to be, of supply and 

 exhaustion of fertilizing matters to soils and aliment to 

 plant-s. 



"All vegetable growth is supported, for a small part, by 

 the alimentary principles in the soil, (or by what we under- 

 stand as its fertility), and partly, and for much the larget 

 portion, by matters supplied, either directly or indirectly, 

 from the atmospherp. More than nine-tenths, usually, of 

 the substance of every plant is composed of the same four 

 «lements, three of which — oxygen, nitrogen and carbon — 

 compose the whole atmosphere ; the fourth — hydrogen — is 

 one of the constituent parts of water ; and, also, as a part 

 ol the dissolved water, hydrogen is always present in the 

 atmosphere, and in a great quantiiy. Thus, all these prin- 

 cipal elements of plants are superabundant, and always sur- 

 rounding every growing plant; and from the atmosphere 

 (or through the water in the soil), very much the larger 

 portion of these joint supplies is furnished to plants; and 

 so it is of each particular element, except nitrogen, much 

 the smallest ingredient, and yet the richest and most impor- 

 tant of all organic manuring substances, and of all plants. 

 This, for the greater part, if not for all of its small share 

 in plants, it seems, is not generally derived, even partially, 

 from the air, though so abundant therein, but from the soil, 

 or from organic manures given to the soil. 



"But, though bountiful nature has offered these chief, 

 alimentary principles and ingredients of vegetable growth 

 in as inexhaustible profusion as the atmosphere itself which 

 they compose, still, their availability and beneficial use fot 



