( 78 ) 



The use of this table will be made evident 

 by a practical example quoted from Boussin- 

 gault's "Economie rurale," vol. 2, p. 149. 



"The pressed oil cakes (marc of oleaginous 

 seeds) are in demand this year, (1842) and it 

 is desirable to know if there is any advantage 

 in their application to the soil for the cultiva- 

 tion of wheat. The inference to be drawn, 

 and it is otherwise the least favourable, is that 

 the wheat abstracts from the soil the whole of 

 its Nitrogen, save that derived from the at- 

 mosphere. In the second place, let us admit 

 that all the Nitrogen of the marc is appropri- 

 ated during the culture. Under certain con- 

 ditions of heat and moisture, these supposi- 

 tions may be realized. In either case, the ac- 

 tive matter left in the soil exerts its influence 

 in the sequent years." 



" Observe now the principles of the ques- 

 tion : 



1. As an average, the amount of Nitrogen 

 in the Becihelbronn wheat is 0.025. 



2. In the straw of 1S41, there is 0.003 Ni- 

 trogen. 



3. The marc of Cameline, the use of which 

 is proposed, contains 0.055. Its actual price 

 (in powder) is 70 cts. per 100 pounds. 



