Sect. V. Agriculture and Vegetation. 169 



into the fame hole out of which it was dug. 

 Clay, which has fo few putrefcent particles, 

 is the moft adhefive foil of any. We have 

 feen already how much (hells, when they 

 begin to putrefy, open the foil. 



BUT there are other comports, though 

 not of the putrefiable fort, which have this 

 attenuating power in a flrong degree. In 

 this clafs are all the marls, but efpecially 

 the fofteft, fuch as the clay marl. We 

 have found how readily they lofe all ad- 

 hefion in water, and fall down into a 

 powder. The fame power they commu- 

 nicate to other earth, even to the moft ad- 

 hefive. The following experiment is a 

 proof of this. 



Exp. 38. Take equal parts of marl and 

 clay, mix them well together, and dry 

 them -, when this compounded fubftance is 

 put into water, it falls by degrees to the 

 bottom of the glafs in the fhape of a 

 powder, while a ball of pure clay remains 



quite 



