152 Agricultural Chemistry. [March, 



as that from the hog-pen, &c., is because it yields more ammonia 

 directly to the plant: also, of guano, night soil, &c., near the 

 roots of plants. 



2Q. The striking advantage of mxick, when the roots of rlants 

 have access to it. 



27. The well known fact of the rapid growth of il^c grape, 

 when the roots penetrate to the reservoir of night soil. 



28. The imitation of nature in the general use of manures. 



29. The preparation of composts, so conducted that the vege- 

 table nutriment may be retained in it, and the roots of plants have 

 direct access to that compost. 



30. The improved mode of retaining the ammonia of ferment- 

 ing animal and vegetable matter, by ground gypsum, and of mixing 

 earth, gypsum, &c., with the droppings of cattle and horses, be- 

 cause earths and porous substances absorb the ammonia, and then 

 burying this prepared manure so as to be accessible to the roots of 

 plants. 



31. To point the attention to no more facts — these are utterly 

 unaccountable, if manures are not actually one source, and no in- 

 considerable source, of carbonic acid and ammonia for direct sup- 

 port and nutriment of plants. And Liebig states, p. 90, " that 

 the proportion of azotized matters in plants is augmented by giv-, 

 ing them a larger supply of ammonia conveyed in the form of 

 animal manure." Here is a virtual admission of the facts already 

 stated, and of the reason for the facts. 



32. If manvres are merely the ashes of anintal and vegetable 

 matter, then the supply of ashes is all the dressing actually neces- 

 sary in agriculture — the ashes of the plants to be cultivated! 



33. That prairies are covered with dense vegetation, while 

 they receive from year to year only the ashes which the fires leave 

 upon them, cannot be a satisfactory argument, until the soil is 

 proved to be destitute of animal and vegetable matter, and that 

 neither animal nor vegetable manures increase the productiveness 

 of the soil already possessing the necessary inorganic substances. 



34. That feeding in a poor soil a plant with the ashes of its 

 kind, should be followed with increased productiveness, is to be 

 <ixpected as a natural result; but let it be proved by experiment, 

 that in a soil possessing all the inorganic elements, the addition 

 of vegetable and animal manure, and especially of the compost 

 duly prepared, or the im))rove(l mixtuie from the stable, does not 

 augment the gix)wth. Let the plant be dressed with the proper 

 ashes in one case, with and without the ashes and with the im- 

 proved mixture in the other, and the experimcntum crucis, the 

 adequate test, will have been applied. 



35. Liebig asks why the " absorption of carbon from the at- 

 mosphere is doubted by all botanists and vegetable physiologists; 



