AGRICULTURE WITH CHEMISTRY. I7 i 



for which reason burned clay, or brick dust, has in pre- 

 ference been recommended, as an article to be added to 

 stiff clayey soils. There are some soils consisting almost 

 exclusively of sand and sea shells, which are astonishingly 

 fruitful ; small shells may therefore be used where clay 

 is not to be had, although it is very seldom that sand is 

 not accompanied by clay at a greater or less depth. In 

 situations, where the clay lies at too great a depth for 

 open work, and where props or pit timber are to be 

 procured at a cheap rate, it may be wrought by shafting 

 and under-ground mining. This idea is a novel one, but 

 in some situations it probably might be carried into exe- 

 cution with advantage. As shells consist of calcareous 

 matter, lime-rubbish, or eff'ette-Yim^ would, for the same 

 reason, be of service to sandy soils ; although lime opens 

 a stiff soil, it is found to have an opposite effeft on a 

 loose sandy soil : still there is not any application to suck 

 a soil, so proper or so fitted as marl, with the assistance 

 of proper dunging, in the rotation of the farm; care 

 being had not to injure such forced or artificial soils by 

 a too frequent and an improper use of the plough, the bad 

 effects of which are beginning to be felt in the County 

 of Norfolk. 



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