LEAVES AEE THE MANURE OP TREES. 543 



For these reasons the practice of removing the leaves which fall in 

 shrubberies, in order to preserve neatness, cannot be too much con- 

 demned. Such leaves, when dried, contain from 5 to 101b. of inorganic 

 matter, suited for the food of plants, in every lOOlbs. ; and this is 

 generally enclosed in a vegetable tissue, which runs rapidly to decay. 

 It is only otherwise with the hard leaves of certain resinous evergreens, 

 such as Pine-trees. Neatness, no doubt, must be observed ; and this 

 will be sufficiently consulted if leaves are swept from walks and lawns, 

 and cast upon the borders in heaps, where they may lie and decay tUl 

 the winter has arrived, when they can be spread upon the earth like 

 so much manure. 



The subject of manures has been most fully and ably treated 

 m both a theoretical and agricultural point of view by a great 

 number of accomplished chemists, whose works of themselves 

 form a small library,* to which the reader is referred. In this 

 place it would be superfluous, even were it possible, to present any 

 other than the slightest possible sketch of so great an enquiry. 



In considering the action of manure there are two points 

 which more especially demand attention — the one, what constir 

 tutes the more important part of the food of plants in general : 

 the other, what special food certain kinds of plants are known to 



* Among these may he more partioulaily mentioned the foUovritng ; — 



Anderson, in the Jowmal of the Highlamd, Society. 



Boussingaiilt, Eamomie Rwale consid4r4e dwns ses rapports avec la Chimie, la 

 PAygigue, et la MMorologie. 



Vawa, A Milch Mammal for Fa/rmers. 



Daubeny, Three Leclmrea on Agrioidtv/re, Papers m the Jowrnal of the Agricultu/ral 

 Society, &e. 



De Qasparin, Covers cl! Agriedtm-e, 



Dumas, Chemistry of Orgamio Life. 



Johnson, J. F. W., Lectures on Agrwultwral Chemistry, and Agriculfv/ral Chemistry. 



Lawes, Vanoms Papers imthe Cfardeners' Chronicle, Jowmal of SoyalAgricvltwral 

 Society, Transactions of British Association, &c. 



Xiebig, Chemistry in its Applications to AgriauMwe and Physiology. 



Mulder, Chemistry of Vegetaile and Animal Physiology, 



Payen, Chimie IndustrieUe, 



Playfeir, in Morton's Encyclopwdia of Agricultwe. 



Sohubler's Agricultu/r-Chemie, 



Solly, E., Rural Chemistry, aaid Various Papers in the Tramactions of the horti- 

 cultural Society, &o. 



Sprengel, Chemie der Pfla/neen, Bodenhmde, Lehre von Danger, Lehre «om den 



Voloker, in Morton's Encyclopaedia of AgricuUwre. 



Way, in Morton's Encyclopcedia of Agricultare, and in the Jownal of the JRoyai 

 Agriailtwal Society, 



