98 ON MANURES. 



will lose all offensive smell, and none of the ammonia 

 which forms there can be lost ; for ammonia and sul- 

 phate of lime cannot be brought together without mutual 

 decomposition, forming carbonate of lime (chalk) and 

 sulphate of ammonia, which are destitute of all smell, 

 and according to Liebig, the greatest fertilizers of soils; 

 for they contain carbonic acid and ammonia, which, with 

 water, contain the elements necessary to the support of 

 ve2;etables or animals. The same substances are the 

 ultimate products of decay and putrefaction ; and thus 

 death, the complete dissolution of an existing generation, 

 becomes the source of life to a new one. 



Contrary to all received notions among farmers, and 

 hitherto among scientific men also, Liebig asserts that 

 geine, humus or vegetable mould are not the food of 

 plants, and declares that so far from humus being ex- 

 tracted from the soil, it is in fact increased by cultiva- 

 tion ; as in the case of a forest, the more abundant the 

 growth of wood upon it, the greater the amount of hu- 

 mus upon the soil, where the debris (leaves annually 

 thrown off,) is suffered to remain upon the land ; and 

 contends that after the leaves are formed, plants derive 

 their nourishment chiefly from the atmosphere. On this, 

 Dr. Dana remarks, " as regards Liebig there are so 

 many points to be settled in vegetable physiology, that 

 his views can be considered at present only as highly 

 ingenious, bold, and counter to experience." Liebig 

 says, that " when vegetable mould is placed in a vessel 

 full of air, it extracts oxygen therefrom with greater ra- 

 pidity than decayed wood, and replaces it by an equal 

 volume of carbonic acid." But this is only a partial 

 view of the action of air upon geine ; it produces not 

 only carbonic acid but water also, by uniting with the 

 hydrogen of the geine. The amount of water proceed- 

 ing from this cause is truly astonishing. It has been 

 found by actual experiment,* equal per hour from an acre 

 of fresh ploughed sward to 950 lbs., while the undis- 



* These interesting facts, for which Dr. Dana refers to Nicholson's Journal, 

 Vol. 2.i, pages 51 — 57, induced me to obtain and examine the paper which con- 

 tains thcnj. The experiments are so interesting and important that I have been 



