THE GREEN-HOUSE. 



133 



especially where the leaves of the pine and fir tribe 

 are used, forms an excellent substitute in most cases. 



Sand, for the purpose of mixing with loam or peat, 

 or for being used alone in striking the more difficult 

 cuttings, may either be obtained from pits, rivers, or 

 by pounding sandstone. The siftings of gravel are 

 generally unsuitable, as earthy and containing a good 

 deal of oxide of iron, known by the brown or yellow 

 colour of such sand. Good sand is generally white, 

 or but slightly tinged. 



Besides loam, peat, and sand, some rubbish of old 

 buildings will be occasionally wanted for succulents, 

 though sand answers nearly if not entirely as well. 

 This material is best obtained when wanted ; for when 

 kept in a compost ground for a year or two, and 

 turned over with the other soils, it assumes the cha- 

 racter of a limy earth. 



Leaf-mould or vegetable mould may be considered 

 more in the light of a manure than of an earth. It is 

 formed by collecting leaves together in heaps, carry- 

 ing them to the compost ground, or space in some in- 

 conspicuous part of the garden devoted to moulds, 

 dungs, and other stock articles, and there laying them 

 in ridges, and turning them over three or four times 

 a year. It is natural to suppose that the nature or 

 kind of the leaves collected will have a material in- 

 fluence on the mould produced ; it is not however 

 ascertained to what extent this is the case. Speechly 

 collected oak leaves chiefly as requiring longer time 

 to decay, and for that reason being more suitable to 



