464 



COAL ASHES VALUABLE AS MANURE. 



coal ashes might not prove suitable by sup- 

 plying them with mineral matter. 



If you, sir, can inform us of their practi- 

 cal uses in any way, you will at least much 

 oblige your subscriber, West Jersey. 



January^ 1S49. 



Answer. — The only analysis of our an- 

 thracite coal ashes, that we have seen, is 

 the following, by Professor Emmons, of Al- 

 bany : 



Analysis Peach Mountain Coal — Gray Ash. 



Silex and silicates, 70.34 



Sulphuric acid, 1.50 



Chlorine, 0.06 



Carbonate of lime, 8.36 



Phosphate of lime and phosphate peroxide of iron, 4.. 50 



Carbonate of magnesia, 1.84 



Alumina and peroxide of iron, 2.00 



97.50 



Prof. Emmons adds to the above analy- 

 sis, that " we may suspect the presence of 

 phosphate of lime in coal ashes, and hence, 

 practically, that they are of importance in 

 agriculture, even though we omit to notice 

 the carbonate of lime and magnesia which 

 they contain." 



Now to make the matter plain, let us 

 compare roughly the value of coal ashes, as 

 regards lime. Sec, with the ashes of the 

 oak tree, one of the commonest kinds of 

 fuel. 



According to an analysis of the Royal 

 Oak, (Liebig's,) the ashe^of that tree con- 

 tain over 50 per cent, of lime, over 5 of 

 potash, 3 of magnesia, and not one part of 

 silica. Another analysis of the White Oak, 

 (Berthier's,) gives 3 per cent, of silica. 

 Let us put the two ashes in contrast, so as 

 to show the proportional value in lime, 

 potash, &c. 



Coal Ashes. 



Lime, 8.36 



Phosphates, 4.50 



Silica, 70. .34 



Oak Ashes. 



Lime, 50.58 



Potash, 5.65 



Silica, 3.37 



Or Elm Ashes. 



Lime 47.80 



Potash, 21.92 



Silica, 3.07 



A comparison of the above will show 

 that fresh wood ashes contains about six 



times as much lime as coal ashes ; and 

 that it is also far richer in potash, which 

 exists in but very small proportion in coal 

 ashes. It is evident that though by no 

 means valueless, in these ingredients, coal 

 ashes are not comparable in value to wood 

 ashes, where lime, potash, or phosphates 

 are required. 



But the largest part of coal ashes is silex 

 and the silicates. Our readers must not 

 look upon these as representing sand or 

 flint glass ; for a considerable part of silica 

 is soluble under certain conditions, espe- 

 cially in clayey soils, and thus enters quite 

 largely into the composition of certain plants. 

 Some plants, such as the oak or the apple, 

 contain very little silica, — say from 1 to 3 

 per cent. But Indian corn, (the stalk,) 

 contains 29 per cent., rye 64 per cent., oats 

 53 ; hence it is evident, that if coal ashes 

 contain a large per centage of silica, they 

 must be highly useful to these crops, even 

 though they contain little lime, &c. 



We have before recommended coal ashes, 

 as particularly well adapted for the cherry 

 tree. This advice was founded on acci- 

 dental experience, and not upon scientific 

 knowledge. But a little investigation ex- 

 plains the reason. The bark of the cherry 

 tree contains (Liebig) 19 per cent, of silica, 

 while that of the apple or pear contains not 

 a i per cent. Hence, it is easy to see why 

 coal ashes would produce little or no good 

 effect on the pear or the apple, as compared 

 with the cherry tree. 



As the bark of the grape-vine contains 

 (Emmons) 14 per cent, of silex, there can 

 be no doubt that coal ashes form a valuable 

 manure for this plant. 



As silica is only rendered soluble by an 

 alkali, such as potash or soda, it is easy to 

 see why coal ashes are more beneficial on 

 clayey than on sandy soils, (besides render- 

 ing the former lighter.) Clay soils almost 



