162 MAlfURES. 



VARIOUS OTHER EARTHY MANURES. 

 LEACHED ASHES. 



Among the eartlij manures which have not yet 

 heen mentioned, — not coming strictly under any of 

 the preceding heads, — is the one known as hacked 

 ashes. 



Tliese are, of course, nuich less valuable than ashes 

 from which the potash has not been leached out ; still, 

 as potash is generally made, the leaching is not very 

 complete, and a considerable quantity of this sub- 

 stance, available to plants, is left in them. In addi- 

 tion to this, they contain some phosphoric acid and 

 silicic acid, which add to their value. Practically, 

 they are held in high esteem in all localities where 

 they can be obtained at a moderate cost of transport 

 ation. Care, however, should be taken, not to pur- 

 chase ashes which have been made in lime-kilns, as 

 these generally contain a large cpiantitj' of lime, 

 which is not worth so high a price as the ashes. 



OLD MORTAR. 



Old mortar is a valuable manure, because it con- 

 tains not only lime, but compounds of nitric acid 

 with alkalies, — called nitrates. 



These are slowly formed in the mortar by the 

 changing of the nitrogen of the hair (in the mortar) 

 and of the ammonia received from the atmosphere 

 into nitric acid, and the union of this with the 



