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cases composed by new arrangements of the elements 

 in air or water. What may be our ultimate view of 

 the laws of chemistry, or how far our ideas of element- 

 ary principles may be simplified, it is impossible to say. 

 We can only reason from facts. We cannot imitate 

 the powers of composition belonging to vegetable 

 structures; but at least we can understand them: and 

 as far as our researches have gone, it appears that in 

 vegetation compound forms are uniformly produced, 

 from simpler ones; and elements in the soil, ,the at- 

 mosphere, and the earth absorbed and made parts of 

 beautiful diversified structures. 



The views which have been just developed lead 

 to correct ideas of the operation of these manures 

 which are not necessarily the result of decayed organi- 

 zed bodies, and which are not composed of different 

 proportions of carbon, hydrogene, oxygene and azote. 

 They must produce their effect, either by becom- 

 ing a constituent part of the plant, or by acting upon 

 its more essential food, so as to render it more fitted 

 for the purposes of vegetable life. 



The only substances which can with propriety be 

 called fossile manures, and which are found unmixed 

 with the remains of any organized beings, are certain 

 alkaline earths or alkalies, and their combinations. 



The only alkaline earths which have been hither- 

 to applied in this way, are lime and magnesia. Potassa 

 and soda, the two fixed alkalies, are both used in 

 certain of their chemical compounds. I shall state in 

 succession such facts as have come to my knowledge 

 respecting each of these bodies in their applications to 



