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very small coal-dust, which is the refuse after what is called 

 riddled slack is extracted. It is again an interesting inquiry 

 — Can this be made useful in the raw or unburnt state ? for, 

 being so small, and lying so close, it refuses to be consumed 

 by itself. Pure coal is composed of oxygen, hydrogen, 

 nitrogen, and carbon, in different proportions, according to 

 the nature of the coal : none of these constituents are in them- 

 selves injurious to vegetation, and, if there be any thing dele- 

 terious in the application of coal to land, it appears to me that 

 it must arise from the extraneous matter there found ; the 

 bad effects of which may, I conceive, not only be neutralized 

 by the addition of lime, or other correctives, but may, very 

 probably, be rendered actually fertilizing. This experiment 

 I am now trying, having made a compost heap of one-fourth 

 lime and three-fourths coal-dust, which is applied both to 

 wheat and grass land, the result of which cannot be properly 

 appreciated until the crops arrive nearer to maturity, but at 

 present the wheat looks promising. As evidence that lime 

 does at any rate neutralize any bad effects arising from an 

 excess of small coal being scattered over the surface of land, 

 I beg to refer to a letter in the Quarterly Journal of Agricul- 

 ture, dated September, 1828. The writer says: — 



" A farm which I occupy has been completely undermined 

 in working for coal. As the seam is near the surface, 

 " great injury has been occasioned by the small coal remain- 

 " ing upon the surface, and getting mixed with the soil. 

 " The numerous places where either the coal or water 

 has been raised, were either quite barren, or, if sown 

 " with corn, though it frequently vegetated, yet it always 

 " became unhealthy, and shrivelled up before the harvest. 

 " I tried removing and mixing it up with the soil, or entirely 

 " covering it over. These methods were only partially suc- 

 " cessful, and could only be accomplished at a considerable 

 '* expense. I had somewhere heard that lime, if applied in 



