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XXXII. On the Application of Manure in a liquid Form to 

 Plants in Pots. By Thomas Andrew Knight, Esq. 

 F.R.S. $c. President. 



Read May 17th, 1814. 



The quantity of earth, which the most firm and solid parts 

 of trees afford by analysis, is well known to be very small ; 

 and even the species of these earths have been proved, by 

 the younger Saussure, to be dependant, to a great extent, 

 upon the component parts of the soil, in which the trees 

 happen to have grown. A large extent and depth of soil 

 seem therefore to be no further requisite to trees than to 

 afford them a regular supply of water, and a sufficient quan- 

 tity of organizable matter ; and the rapid growth of plants 

 of every kind, when their roots are confined in a pot to a 

 small quantity of mould, till that becomes exhausted, proves 

 sufficiently the truth of this position. 



I have shewn in a former communication* that a seedling 

 Plum-stock, growing in a small pot, attained the height of 

 nine feet seven inches, in a single season ; which is, I believe, 

 a much greater height than any seedling tree of that species 

 was ever seen to attain in the open soil. But the quantity of 

 earth, which a small pot contains, soon becomes exhausted, 

 relatively to one kind of plant ; though it may be still fertile 

 relatively to others : and the size of the pot cannot be 

 changed sufficiently often to remedy this loss of fertility ; 

 and if it were ever so frequently changed, the mass of mould, 

 which each successive emission of roots would enclose, must 

 remain the same. 



* See Vol. i. page 249- 



