S2 



A TREATISE ON THE CONNECTION OF 



IRON".. 



The metallic substance contained in the greatcdC 

 quantity in soils, is iron ; it exists therein in a variety of 

 states — in a metallic state — in the state of yellow ochre, 

 or iron combined with iixable air — in the state of red 

 ochre, or iron combined with pnre air or oxygen — and 

 in the state of pyrites, or iron mineralized by sulphur. 

 Pyrites are only found in such soils as have not long 

 been under cultivation, or exposed to the action of the 

 air for a sufficient length of time, so as to decompose 

 the pyrites by the combination of pure air ; a process in 

 this Treatise called oxygenation. By this means, the 

 vitriolic acid is formed, and which, as it forms, joins. 

 M'ith the earth of iron, the other constituent part of 

 the pyrites, and forms green vitriol. This salt, in poor 

 soils, containing little calcareous matter, is extremely 

 injurious to the growth of plants, the bad effects of 

 which to ^^getatiorr may be corrected by dung, and. 

 urine of cattle — by lime — chalk — magnesia — and alkaline 

 salts. With lime or chalk,, the acid of the green vitriol 



forms 



