What 18 the soil made of? 6 



with a long clean nail. First of all it chars, then there 

 is a little sparkling, but not much, finally the soil turns 

 red and does not change any further no matter how 

 much it is heated. The shade of red will at once be re- 

 cognised as brick red or terra cotta, indeed "terra cotta '* 

 means " baked earth." When the soil is cold it should 

 be examined again ; it has become very hard and the 

 plant remains have either disappeared or have changed 

 to ash and crumble away directly they are touched. 

 On weighing a further loss is discovered, which was in 

 our experiment : — 



Weight of top soil after drying but before burning... 83 decigrams 

 » ii» >j »5 >i ♦» alter ), ... /o ,, 



The part that burnt away weighed 7 „ 



Weight of subsoil after drying but before burning ... 87 decigrams 

 « « )) » » »> after „ ... 84 „ 



The part that burnt away weighed 3 „ 



These results are entered on the column in Fig. 2. 



The surface soil is seen to contain more material 

 that will burn away than the subsoil does. When the 

 burnt soil is moistened it does not become dark and 

 sticky like it did before, it has completely changed and 

 cannot be made into soil again. It is more like brick 

 dust than soil. 



For further experiments we shall want a fresh 

 portion of the original soil. 



On a wet afternoon something was noticed that 

 enabled us to get a little further with our studies. The 

 rain water ran down a sloping piece of ground in a tiny 

 channel it had made ; the streamlet was very muddy, 

 and at first it was thought that all the soil was washed 

 away. But we soon saw that the channel was lined 



