CHALK IN SOILS. 107 



but little thought when an appreciable amount 

 is present in the soil, but some soils contain so 

 little that the addition of dressings of carbon- 

 ate of lime, as chalk or limestone, at long inter- 

 vals, may be expected to add to their fertility. 



PRACTICAL WOKK. 



1. Dig a hole or trench in the garden, and 

 note the character of the soil from the surface 

 downwards. This trench may perhaps be 

 designed to fulfil some useful purpose or the 

 observations may be made when occasion arises 

 for digging thus deeply. 



2. Ascertain, if possible, the character of 

 the rock lying beneath the garden either by 

 digging down to it or by observing it at some 

 place in the immediate neighbourhood where it 

 comes to the surface. 



3. Collect the different kinds of stones to 

 be found in the garden soil and note whether 

 they are of a similar character to the under- 

 lying rock. If other kinds of stones are found 

 endeavour to explain whence they are probably 

 derived. (A selection of these stones should 

 be kept in the school). 



