VEGETABLE MATTER IN SOILS. 113 



dry in the air for a day or two, and then put it 

 into the kitchen tire for some hours. When 

 cold compare it with a portion of fresh, un- 

 burned clay. Note that, although it is still 

 able to absorb water by capillarity, it has lost 

 its plastic character and can no longer be 

 moulded into shape by the hand. Crush it to 

 powder and moisten with water ; the plasticity 

 is not restored, it is permanently lost. Note 

 also the change in colour. 



VEGETABLE MATTER IN SOILS. 



1. A place should be set apart in the school 

 garden for a compost heap. All available re- 

 fuse should be collected and placed on this 

 heap, and, at intervals, a layer of soil should be 

 thrown over it to promote decay and prevent 

 unpleasant smells. The heap should be kept 

 damp throughout. Care should be taken to 

 select the place for the compost heap where it 

 will not be unsightly, and, if a low hedge is 

 planted round the spot, it need not disfigure 

 the neatest garden. It is convenient to have 

 two heaps one in process of formation, the 

 other ready for use. 



To illustrate the influence of vegetable 

 matter on soil fertility, select in the school 

 garden two beds, of equal size, with similar soil, 



