THE ASH OF PLANTS. 175 



posed of very vigorous plants ; 2, of medium ; and, 3, of 

 very weak plants. He analyzed the ashes of each parcel, 

 with results as below : 



123 



Silica 27.0 39.9 42.0 



Sulphuric acid 4.8 4.1 5.6 



Phosphoric acid 8.2 8.5 8.8 



Chlorine 6.7 5.8 4.7 



Oxide of Iron 0.4 0.5 1.0 



Lime 6.1 5.4 5.1 



Magnesia, Potash and Soda. 45.3 34.3 30.4 



Here we notice that the ash of the weak plants con- 

 tains 15 per cent less of alkalies, and 15 per cent more of 

 silica, than that of the vigorous ones, while the propor- 

 tion of the other ingredients is not greatly different. 



Zoeller (Liebig's Erndhrung der Vegetabilien, p. 340) 

 examined the ash of two specimens of clover which grew 

 on the same soil and under similar circumstances, save 

 that one, from being shaded by a tree, was less fully de- 

 veloped than the other. 



Six weeks after the sowing of the seed, the clover was 

 cut, and gave the following results on partial analysis : 



Shaded clover. Unshaded clover. 



Alkalies 54.9 36.2 



Lime 14.2 22.8 



Silica 5.5 12.4 



c. The variety of the plant or the relative development 

 of its parts must obviously influence the composition of 

 the ash taken as a whole, since the parts themselves are 

 unlike in composition. 



Herapath (Qu. Jour. Chem. Soc., II, p. 20) analyzed 

 the ashes of the tubers of five varieties of potatoes, raised 

 on the same soil and under precisely similar circum- 

 stances. His results are as follows : 



White Prince's Axbridge 



Apple. Beauty. Kidney. Magpie. Forty-fold. 



Potash 69.7 65.2 70.6 70.0 62.1 



Chloride of Sodium.. 2.5 



Lime 3.0 1.8 5.0 5.0 3.3 



Magnesia 6.5 5.5 5.0 2.1 3.5 



Phosphoric acid 17.2 20.8 14.9 14.4 30.7 



Sulphuric acid 3.6 6.0 4.3 7.5 7.9 



Silica 0.2 



