62 TZtf Principles of Part II. 



vitriolic acid. From other experiments 

 which I have made, the bad effects do not 

 feem to arife from the vitriolic acid ; elpe- 

 cially as the acid here appears to be very 

 volatile. But we have already difcovered 

 the pernicious quality of fait of fleel. Nor 

 is it any wonder, that it mould exert itfelf 

 fo powerfully here, coniidering the quan- 

 tity of this body laid on ground inftead of 

 marl, and the great quantity of this fait in 

 it. The foil muft be perfectly faturated 

 with it. 



BUT how mall we correct the poifonous 

 quality, if, by miftake, this or fuch like 

 bodies mould be ufed ? For coal produces 

 the fame effects from the fame caufe. There 

 feems to be no other method but that of 

 decompoiing the fait - t fo that the fteely part 

 may be no longer diffolvable in water. The 

 air, by volatilizing the acid, and leaving the 

 chalybeate particles behind, has that ef- 

 fect, by gentle degrees, on fait of fleel, 

 when it is diffolved in water. But, in the 

 prefent cafe, the acid would not reach the 



fait, 



