DR. DAUBENY ON THE ROTATION OP CROPS, ETC. 



225 



The above analyses of potatoes, it may be observed, agree more nearly with 

 BoussiNGAULT than with Sprengel, as will appear by the following Table :— 



The correspondence between the standard crop analysed by Mr. Way and the one 

 analysed by Boussingault, is in many particulars exceedingly close ; there is indeed 

 an excess of magnesia and some little deficiency of potass, but if the potassium 

 present in 7*6 of chloride (which is equivalent to 4'0) be represented as potass, it will 

 amount to 4-8, which, added to 43'8, brings up the proportion of potass to 48-6, or 

 to more than that present in the permanent crop. 



Turnips. 



The next kind of crop which we analysed was the turnips, and the following were 

 the results obtained : — 



Standard sort from the neighbourhood of Oxford, contained about 10 of water, 

 and 1 of organic matter. 



1000 grains yielded 3*18 of ashes ; 100 grains of which consisted of — 



Sand and charcoal . 5-28 



Peroxide of iron 11-91 



17*16 



Silica 3-81 



Phosphoric acid 1 2-63 



Sulphuric acid 7*17 



Carbonic acid 7*04 



Chloride of sodium 4*83 



Soda 2-57 



Potass 31-62 



Magnesia 3* 18 



Lime 11'54 



Real ingredients 



101-55 

 17*16 



84-39 



