PHYSICAL AND LITERARY. 3^ 



But when a body containing iron is cal- 

 cined in contadl with an inflamable fub- 

 ftance, that metal immediately afliimes 

 its diflinguifhing qualities, and of con- 

 fequence becomes obedient to the magnet, 

 and foluble in acids. Therefore, when 

 our marie, in its natural ftate, was exa- 

 mined by the acid of fea fait, the iron 

 contained in it: fufFered no change, but 

 remained in the filter as part of the refi- 

 due. On the other hand, when this 

 marie, furrounded on all fides by burn- 

 ing pit-coal, was properly calcined, its i- 

 ron became foluble in acids, and confe- 

 quently fit to pafs thro' the filter, with 

 the calcarious earth invifibly fufpended 

 in the acid of fea fait. Thus it is evi- 

 dent, that, in all marles containing iron, 



the 



a tinfture of galls. The water which contained our fo- 

 lution became thereby confiderably darker in its co- 

 Jour than the other. Therefore, ten grains of the pre- 

 cipitated powder contained more iron than 14; grains 

 of pure fait of fteel. This marie commim'cated none 

 of its iron to plain water. About a third part of its 

 fubftance was foluble in the acid of fea fait. 



