10 OF THE ASSIMILATION OF CARBON. 



quantity of the alkaline bases contained in the 

 ashes of plants, let us calculate the amount of hu- 

 mic acid which might be assimilated in this man- 

 ner. Let us admit, likewise, that potash, soda, and 

 the oxides of iron and manganese have the same 

 capacity of saturation as lime with respect to hu- 

 mic acid, and then we may take as the basis of our 

 calculation the analysis of M. Berthier, who found 

 that 1000 Ibs. of dry fir- wood yielded 4 Ibs. of 

 ashes, and that in every 100 Ibs. of these ashes, 

 after the chloride of potassium and sulphate of 

 potash were extracted, 53 Ibs. consisted of the basic 

 metallic oxides, potash, soda, lime, magnesia, iron, 

 and manganese. 



40,000 square feet* Hessian measure of wood- 

 land yield annually, according to Dr. Heyer, on an 

 average, 2650 Ibs. Hessian of dry fir- wood, which 

 contain 5*6 Ibs. I \ essian of metallic oxides. 



Now, according to the estimates of Malaguti and 

 Sprengel, 1 Ib. Hessian of lime combines chemically 

 with 10*9 Ibs. Hessian of humic acid; 5 '6 Ibs. of 

 the metallic oxides would accordingly introduce 

 into the trees 61 Ibs. Hessian of humic acid, which, 

 admitting humic acid to contain 58 per cent, of 

 carbon, would correspond to 91 Ibs. Hessian of 

 dry wood. But we have seen that 2650 Ibs. of fir- 

 wood are really produced. 



* [The numbers in the text in Hessian feet and pounds will show 

 a proportion to other numbers equally well as if they were reduced to 

 their equivalents in English. For those, however, who prefer knowing 

 the exact English quantities, a table of equivalents is given at the end.] 



