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INTRODUCTION. 



My inducement to commence this work, after it was fuggefted to 



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'me by the letters of Sir John Sinclair, was a belief, that the expe- 

 riments and obfervations already made on the growth of plants, with 

 the modern improvements in chemiftry, were fufficiently numerous 

 .and accurate for the eftablifhment of a true theory of vegetation .; 

 fo much wanted to conned the various fads in the memory, to ap- 

 preciate their value, and "to compare them with each other ; and 



finally to direct the profecutiori of future experiments to ufefiil 

 purpofes. 





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1>HyT0L0GlA- 





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