90 SAND-WASTES OF FRANCE. 



In consequence of this, it is remarked by Wessley, the level of the 

 subterranean water stands high in drift sand layers ; and standing or 

 running waters can with ease diffuse themselves sideways in sand 

 layers. 



The power of absorbing nutritive elements of vegetation is 

 possessed by sand in a degree remarkably limited in comparison 

 with the degree in which it is possessed by other soil. According to 

 experiments by Grouven, 1,000 grammes of pressed northern diluvial 

 sand, field soil absorbed : 



Ofpotash, ... ... ... 24-1 



Of ammonia, ... ... ... 18'6 



Of phosphoric acid, ... ... 6 - 4 



And the same quantity of loamy northern diluvial sand, field soil 

 absorbed : 



Ofpotash, ... ... ... 22-5 



Of ammonia, ... ... ... 21 -5 



Of phosphorio acid, ... ... 2 1 - 5 



While 22 samples of turnip field soil of different kinds absorbed : 

 Ofpotash, ... ... from 66 to 137 



Of ammonia, ... ... from 35 to 134 



Of phosphorio acid, ... from 32 to 135 



The power of absorbing ammonia from the atmosphere is, we see, 

 possessed in the lowest degree by sand. Clay, mergel, and humus 

 surpass all other soil in this. It is the same with the power of 

 absorbing carbonic atmosphere from the air possessed by all of these 

 substances in a wet state ; this is least of all in sand, but it exists 

 in the greatest degree in humus. 



This power of the sand increases with the fineness of its particles ; 

 it may be observed to be proportional to the minute sub-division 

 of the bodies operated on, and this property may be intensified 

 in the sand by the admixture with it of the other substances 

 mentioned. 



