COMPOSITION OF WOOD ASHES, AND USE AS A MANURE. 363 



have almost universally been found to follow the use of wood ashes and 

 of the ash of other vegetables in the cultivation of the land. 



The quality of the ash left by plants when burned varies, as we have 

 already had occasion to remark (p. 216), with a variety of circum- 

 stances. It always consists, however, of a mixture in variable propor- 

 tions of carbonates, silicates, sulphates, and phosphates of potash, soda, 

 lime, and magnesia, with certain other substances present in smaller 

 quantity, yet more or less necessary, it may be presumed, to vegetable 

 growth. Thus, according to Sprengel, the ash of the red beech, the oak 

 and the Scotch fir ( pinus sylvestris), consists of 



Bo/i n^^v^K r»,i, Scotch Pitch Pine. 



Red Beech. Oak. p^ (Berthier.) 



Silica 5-52 2695 659 750 



Alumina 2-33 



Oxide of Iron. . . . 377 814 1703 IMO 



Oxide of Manganese . 3.85 — — 275 



Lime 25 00 1738 2318 13-60 



Magnesia 500 1'44 502 435 



Potash 22-11 16 20 2-20 14-10 



Soda 3-32 6-73 2 22 20-75 



Sulphuric Acid ... 7-64 336 2-23 3-45 



Phosphoric Acid. . . 5-62 1-92 2-75 0-90 



Chlorine 1-84 241 230 



Carbonic Acid . . . 1400 1547 36-48 1750 



100 10^ 100 960 



The composition of these different kinds t f ash is very unlike — that 

 of the pitch pine, for example, being greatly richer in potash and soda, 

 and poorer in lime and phosphoric acid, than that of the Scotch fir — 

 while the beech is richer than any of the others in potash and lime and 

 in the sulphuric and phosphoric acids. The several effects of different 

 kinds of wood ashes when applied to the land will therefore be different- 

 also. 



In England, wood ashes are largely employed in many districts, 

 mixed with bone dust, os a manure for turnips, and often with great 

 success. 4s much as 15 bushels (7i cwt.) of ashes are drilled in per 

 acre with 15 bushels (6 cwt.) of bones. The large quantity of alkali 

 present in the turnip crop (p. 219) may be supposed to explain the 

 good effects which wood ashes have upon it, and may lead us to expect 

 that they would in a similar degree increase the produce of the carrot 

 and of the potatoe.* 



The immediate benefit of wood ash is said to be most perceptible upon 

 leguminous plants (Sprengel), such as lucerne, clover, peas, beans, and 

 vetches. As a top-dressing to grass lands it roots out the moss and pro- 

 motes the growth of white clover. Upon red clover its effects will be 

 more certain if previously mixed with one fourth of its weight of gyp- 

 sum. In small doses of two or three hundred weight (4 to 6 bushels) 

 it may be safely applied even to poor and thin soils, but in large and 

 repeated doses its effects will be too exhausting, unless the soil be either 



* This inference has been verified by Mr. Wharton, of Dryburn, who has obtained an 

 excellent crop of potatoes from newly ploughed-out land by manuring with wood ashes 

 only. 



