224: EG YP TJAN A GKICUL TURK. 



has been accepted as evidence of the satisfactory nature 

 of the solvent employed. 



Manures then may be described as substances which 

 when applied to the soil increase its fertility or productive 

 power, and the three ingredients, nitrogen, phosphoric 

 acid, and potash, are those upon which the value of a 

 manure chiefly depends. They differ so much in their 

 nature and in their action that it is almost impossible to 

 consider them as a whole, while again, fertility, as accept- 

 ed in the broad sense of the term, is dependent upon so 

 many conditions, that some manures influence it in one 

 respect, and others largely in an entirely different manner. 

 In other words, fertility may be promoted in a variety 

 of ways, and according to the functions performed by 

 manures we may divide them into two main classes : 



(1) those which supply the soil directly with plant food. 



(2) those which exercise an indirect action. 



The first class may again be sub-divided into : (a) those 

 which may be called "general" in their nature: they 

 supply the soil with practically all the ingredients neces- 

 sary to plant life, and as they are usually bulky, exercise 

 a considerable effect indirectly on the soil, (b) those 

 which supply the soil with some particular ingredient: 

 they furnish the plant with some ingredient or ingredients 

 in which the soil is lacking, though to a minor extent, 

 they may also exercise an indirect action. 



The second class, consisting of those substances which 

 mainly exercise an indirect influence, is of less importance. 

 Lime may be taken as an example. Though it is possible 

 that this substance may, in a soil actually deficient in it, 



