369 COMPOSITION AND USE OF COAL ASHES. 



"iet the small quantity of saline matter they contain is not to be con- 

 sidered as wholly without effect. For the Dutch ashes are often ap- 

 plied to the land to the extent of two tons an acre — a quantity which, 

 eren when the proportion of alkali does not exceed one per cent., will 

 contain 45 lbs. of potash or soda, equal to twice that weight of sulphates 

 or of common salt. To the minute quantity of saline matters present in 

 them, therefore, peat ashes may owe a portion of their beneficial in- 

 fluence, and to the almost total absence of such compounds from the 

 less valuable sorts, their inferior estimation may have in part arisen. 



In Holland, when applied to the corn crops, they are either ploughed 

 in, drilled in with the seed, or applied as a top dressing to the young 

 shoots in autumn or spring. Lucerne, clover, and meadow grass are 

 dressed with it in spring at the rale of 15 to 18 cwt. per acre, and the 

 latter a second time with an equal quantity after the first cutting. In 

 Belgium the Dutch ashes are applied to clover, rape, potatoes, flax, 

 and peas — but never to barley. In Luneburg the turf ash which 

 abounds in oxide of iron is applied at the rate of 3 or 4 tons per acre, 

 and by this means the physical character of the clay soils, as well as 

 their chemical constitution, is altered nnd improved. 



In England peat is in many places burned for the sake of the ashes 

 it yields. Among the most celebrated for their fertilizing qualities are 

 the reddish turf ashes of Newbury, in Berlnhire. The soil from be- 

 neath which the turf is taken abounds in lime, and the ashes are said to 

 contain from one-fourth to one-third of their weight of gypsum, [Bri- 

 tish Husbandry, ii., p. 334.] They are used largely both in Berkshire 

 and Hampshire, and are chiefly applied to green crops, and especially 

 to clover.* 



g. Coal ashes are a mixture of which the composition is very varia- 

 ble. They consist, however, in general, of lime often in the state of 

 gypsum, of silica, and of alumina mixed with a quantity of bulky and 

 porous cinders or half burnt coal. The ash of a coal from St. Etienne, 

 in France, after all the carbonaceous matter had been burned away, 

 was found by Berthier to consist of 



Alumina, insoluble in acids .... 62 per cent. 



Alumina, soluble 5 " 



Lime 6 " 



Magnesia 8 " 



Oxide of Manganese . ' . . . . 3 " 



Oxide and Sulphuret of Iron . . . . 16 " 



100 



Such a mixture as this would no doubt benefit many soils by the 

 alumina as well as by the lime and magnesia it contains; but in the 

 English and Scotch coal ashes a small quantity of alkaline matter, 

 chiefly soda,f is generally present. The constitution of the ash of our 

 best coals, therefore, may be considered as very nearly resembling that 

 of peat ash, and as susceptible of similar applications. When well 



* 50 bushels per acre (at 3d. a bushel, or 12s. 6d. an acre) increase the clover crop folly 

 one fifth.— Morton « On Soils," p. 170. ' 



t From the common salt with which our coal is ao often impregnated. 



