Wilson — Changes in Soils brought about by Heating. 517 



From these experiments it is clear that the amount of soluble matter in 

 soil is increased by heating. This is shown by : — 



(ffl) Depression of freezing-points of soil extracts, which increases from 006° 

 in the case of soil heated at 60° to 0"19° in the soil heated at 150°. 



(S) The electrical conductivities of the extracts, which show an increase 

 from 36-0 x 10"* in the case of soil heated at 60° to 198 x 10"* in soil heated 

 at 150°. 



In each of the extracts about half the depression of freezing-point was due 

 to electrolytes. 



The increase in the amount of water absorbed by the heated soil indicates 

 a change in the texture of the soil brought about by heating. 



In a further set of experiments soil was prepared in the manner previously 

 described, and allowed to dry at ordinary air temperature during a few days. 



