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suffered it to remain in it till the leaves became yel- 

 low ; the roots were then carefully washed in distil- 

 led water, bruised, and boiled in a small quantity of 

 the same fluid : the decoction of them passed through 

 a filtre was examined by the test of infusion of nut- 

 galls ; the decoction gained a strong tint of purple, 

 which proves that solution of iron had been taken up 

 by the vessels or pores in the roots. 



Vegetable and animal substances, as is shewn by 

 universal experience, are consumed in vegetation ; 

 s and they can only nourish the plant by affording solid 

 matters capable of being dissolved by water, or gas- 

 eous substances capable of being absorbed by the 

 fluids in the leaves of vegetables ; but such parts of 

 them as are rendered gaseous, and that pass into the 

 atmosphere, must produce a comparatively small ef- 

 fect, for gasses soon become diffused through the 

 mass of the surrounding air. The great object in the 

 application of manure should be to make it afford as 

 much soluble matter as possible to the roots of the 

 plants ; and that in a slow and gradual manner, so 

 that it may be entirely consumed in forming the sap 

 or organized parts of the plant. 



Mucilaginous, gelatinous, saccharine, oily, and 

 extractive fluids, and solution of carbonic acid in wa- 

 ter, are substances that in their unchanged states con- 

 tain almost all the principles necessary for the life of 

 plants ; but there are few cases in which they can be 

 applied as manures in their pure forms ; and vegeta- 

 ble manures, in general, contain a great excess of fib- 

 rous and insoluble matter, which must undergo che- 



