218 DR. DAUBENY ON THE ROTATION OF CROPS, ETC. 



Barley. 

 Grown in the same part of the garden as the last, for ten years immanured, 

 distinguished as the shifting crop. 



100 grains of the dried crop, including as before both the straw and the grain, left 

 of ash 6-25 grains. 



100 grains of this ash contained as follows:^ 



Sand and charcoal, extraneous 21*91 



Peroxide of iron, chiefly extraneous ... 2*30 



24-21 



Silica of the plant 36-47 



Phosphoric acid 9*30 



Sulphuric acid . 2-35 



Carbonic acid 1*44 



Chloride of sodium 1*43 



Potass 16-58 



Magnesia 3-58 



Lime 772 



103-08 



Barley. 



Grown in a distinct part of the garden. Soil similar, but recently manured, 

 distinguished as the standard crop. 



100 grains of the dried crop, including as before the straw and grain, gave of 

 ash 7' 15 grains. 



100 grains of this ash contained as follows : — 



Sand and charcoal, extraneous 16*60 



Peroxide of iron, chiefly extraneous . . . 2*30 



18-90 



Silica of the plant . 37*27 



Phosphoric acid 7'^7 



Sulphuric acid 4*37 



Carbonic acid 1-51 



Chloride of sodium 1 -84 



Potass 13*86 



Magnesia 3*96 



Lime 11*81 



101*19 

 It would appear then from the above analyses, that the principal difference between 

 the permanent crop and the two others consisted in the larger amount of soluble 

 silica, which, together with the greater proportion of ash, may have arisen from the 

 straw predominating in quantity over the grain. 



