NITROGEN IN SOILS AND FAR^I-YARD MANURE. 315 



six hours' heating with a sohition of soda, a third, a 

 fourth, or a sixth of the ammonia absorbed by it, and we 

 cannot assert tliat the retained portion has changed its 

 nature, and is no longer ammonia ; so from the comport- 

 ment of the eartli in its natural condition, and under the 

 same circumstances, we cannot conclude that the nitrogen 

 which by distillation cannot be obtained in the form of 

 ammonia, does not, therefore, exist as such in the earth. 



Even if the experiments above described do not afford 

 any proof that all the nitrogen in the ground is in the 

 form of ammonia (a portion, besides, is in most cases pre- 

 sent as nitric acid), there is, on the other hand, no proof 

 furnished to the contrary. 



Strictly speaking, the discussion of the point m ques- 

 tion does not depend on this proof ; for it is sufficient to 

 show here, that the comportment of the soil with respect to 

 the amount of nitrogen in it is exactly the same as that of 

 farm-yard maniure. Only a small portion of the nitrogen 

 in farm-yard manure is separable by distillation with 

 alkahes ; the much larger portion being obtained only by 

 complete decomposition of the substances. 



According to Voelker's analysis, 800 cwt. of fresh farm- 

 yard manure contained — 



1854, November 1855, April 

 lbs. lbs. 



Nitrogen 514 712 



Ammonia I f;71„„ • 27'2j ^ ^ ^ g^.g ^^.^ 



|_in salts 



If we compare with this the amount of separable am- 

 monia and the total nitrogen in the soil at Schleissheim 

 and Bogenhausen, we have — 



800 cwt. of arable soil contain nitrogen 

 Present as separable ammonia 



It is manifest, that when two soils, not particularly rich 

 in nitrogen, contain just as much ammonia as an equal 



