38 A TREATISE ON THE CONNECTION OF 



will require many years before coal, (wrought at a con- 

 siderable depth, and brought to the surface} will, by ex- 

 posure to air, become oxygenated, and attain what coal at 

 a less depth had acquired by the adlion of air and water 

 during many ages. 



"When coal is in a state capable of being rendered so- 

 luble, it is soft and friable ; when rubbed between the 

 fingers it appears like soot; when thrown into the fire 

 it does not burn with any flame; and whilst consum- 

 ing, emits a smell more like unto that from the com- 

 bustion of peat than coal. 



Most fossile coal contains the bases requisite for form- 

 ing, with a combination of pure air or oxygen, the fol- 

 lowing acids, viz. the vitriolic or sulphuric, muriatic, 

 phosphoric, 8cc. 



The acid first formed is the sulphuric. As this is ge- 

 nerated, it combines either with the earth of iron or the 

 earth of magnesia, forming green vitriol and Epsom salt. 

 These salts being very soluble, are readily washed away 

 from the coal by rain or moisture ; after which, by a 



farther 



