161 



Analysis of Water Containing Aluminum Salts 



and Free Sulphuric Acid from an 



Indiana Coal Mine. 



S. D. Conner. 



Within the past year the "writer was called upon to test some drainage 

 water from a coal mine for the Vandalia Coal Company of Terre Haute "with 

 a view of determining whether such "water could be used for irrigation pur- 

 poses. 



A qualitative examination indicated only a trace of chlorides and nitrates, 

 but an abundance of sulphates. 



The folio-wing substances were quantitatively estimated: 



A1 2 (S0 4 ) 3 016 per cent. 



CaS04 141 per cent. 



MgSCh 074 per cent. 



Free H 2 S0 4 D05 per cent. 



Total solids 42 per cent. 



Contrary to expectations, no soluble iron "was found, although a slight 

 floeculent precipitate of iron (probably basic feme sulphate) was noted 

 in the bottom of the bottle, indicating that originally some iron had been 

 in solution. 



In the mining of coal more or less iron pyrites (FeSs) is exposed to the 

 air. This pyrites in the presence of oxygen and moisture is oxidized, forming 

 ferrous sulphate and sulphuric acid. The sulphuric acid coming in contact 

 with clay, shale, etc.. would dissolve calcium, magnesium, aluminum and other 

 basic elements which might be present. Upon continued exposure to air 

 the ferrous sulphate (Fe SO.?) in solution would be oxidized to basic ferric 

 sulphate (Fe(OH)S0 4 ) and precipitated. 



Water such as the writer analyzed is acid in reaction, due to the presence 

 of free sulphuric acid and also to the hydrolysis of the aluminum sulphate. 

 Such water would be injurious to vegetation and consequently unfit for 

 irrigation purposes. 

 50S4 — 11 



