COMPOSITION OF VARIOUS TREES 103 



Gaultheria {Gaultheria procumbens, winter- 

 green, Natural Order, Ericacese) is a hardy ever- 

 green shrub. It prefers a peaty soil in moist 

 rockeries or shady shrubberies. 



The ashes of the wintergreen contain in 100 

 parts : — 



Iron oxide 2 -26 



Manganese dioxide . . . 0"41 



Lime 16-88 



Magnesia 14 "21 



Potash 29-24 



Soda 12-32 



Phosphoric acid .... 4-26 



Sulphuric acid . . . . 3-66 



Chlorine 0-82 



Silica 15-94 



The wintergreen is indigenous to North America, 

 but was introduced into this country in 1762. Its 

 obovate leaves yield on distillation 0"5 per cent, 

 of a volatile oil which consists chiefly of methyl 

 salicylate. It is used in medicine. The bark of 

 the sweet birch (Betula Lenta) also contains a 

 similar oil. 



Genista (Genista pilosa, Natural Order, 

 Leguminosae) is a hardy deciduous flowering shrub. 

 It grows in ordinary soils — preferring sandy and 

 gravelly heaths. 



The ashes of Genista contain in 100 parts ^ : — 



1 A. B. Griffiths, ibid., p. 92. 



