COMPOSITION OF THE ASH. 247 



in many cases with the age of the plant. The following table 1 

 indicates the per cent of ash in a few instances : 



Turnip (fresh) 7 



Sugar beet (fresh) 8 



Potatoes (fresh) 9 



Red clover (fresh) 1.3 



Red clover (dry) 5.6 



Birch-wood (dry) 2 



Apple-tree wood (dry) 1.1 



Walnut-wood (dry) 2.5 



Birch-bark 1.1 



Mulberry leaves (fresh) 1.1 



Horse-chestnut leaves (spring) 2.1 



Horse-chestnut leaves (autumn) 3.0 



Apples (fresh) 3 



Pears (fresh) 4 



Flax-seed 3.2 



Clover-seed 3.6 



Hemp-seed 4.8 



Beech-nuts 2.7 



Wheat-grains 1.7 



Hemp (entire plant) 2.8 



665. Composition of the ash of plants. Examination of trust- 

 worth} 1 analyses of the ash of flowering plants shows that certain 

 elements are always present in it. These are potassium, calcium, 

 magnesium, and phosphorus. Besides these, which always ap- 

 pear in appreciable amount, there are others which are nearly 

 or quite as constant in occurrence, although in some reports of 

 analyses they are not given, because existing in such small pro- 

 portion. They are iron, chlorine, sulphur, and sodium. The 

 elements mentioned are usually recorded in analyses in the fol- 

 lowing combinations : potassa, phosphoric acid, lime, magnesia, 

 sulphuric acid, soda, and ferric oxide. But it is to be observed 

 that the combinations stated in the tabulation of analyses are by 

 no means designed to exhibit all those in which the elements 

 occur in the plant ; for instance, the sodium and potassium are 

 presumably combined with the chlorine. Again, it must be no- 

 ticed that upon combustion the mineral matters in the plant are 

 commingled with a larger or smaller amount of carbonates, the 



1 E. Wolff, Die Mittlere Zusammensetzung der Asche, 1865, p. 77 et seq. 

 See also an excellent revised translation of Wolff's tables in the Appendix of 

 Johnson's "How Crops Grow" (1868). For the percentage of ash in trees 

 and woody plants, as well as the amounts of phosphoric acid and potash found 

 in such ash, see a very valuable table by Storer (Bulletin Bussey Institution, 

 1874, pp. 207-245). 



