434 



On the Chemical Constituents of Crops. 



In order, however, to afford to others the means of appreciating the 

 degree of reliance which may be placed upon his numbers, I have set 

 down side by side the amount of ashes obtained by Sprengel and by 

 Boussingault from the same species of crops, from which it will appear 

 that, unless their fixed ingredients in each case vary in different in- 

 stances materially, they have either not as yet been ascertained with 

 sufficient precision, or were not brought to the same degree of dryness 

 in the two instances, previously to their analysis. 

 I have the honour to be. Sir, 



Your most obedient servant, 



Charles Daubeny. 

 Oxford, Oct, nth, 1842. 



Corrected Table of the Constituents of certain Crops. 



* Given in the former Table 814, in which state the potatoes contained 68* S water, 

 and only 31*2 of vegetable matter. 

 Now as 31-2— 814— 100— 2646. 



XI. — On the Quantity of Minute Ingredients of Soil con- 

 tained in an Acre of Land. By John Hall. 



To H. Handley, Esq. 

 Sir, — The near approach of the annual meeting of the Royal Agri- 

 cultural Society of England has induced me to trouble you with the 

 following remarks on ' Liebig's Analysis of Soils,' because it appears 

 to me that the analysis of soils, as given by him, and set forth in the 

 second edition of his work, edited by Dr. Playfair, is not calculated to 

 be of much utility to practical agriculturists, from the parts or propor- 

 tions being stated in three figures of decimals ; the thousandth part of a 

 unit conveying to the mind scarcely any idea of how much of any earth, 

 salt, or metallic oxide, so represented, is contained in an English acre. 



