VALUE OF AMMONIA AM) NITKIC ACID, 



301 



been similarly made out. Wo have learned that ammonia 

 occurs, naturally, in too small proportion, either in the 

 atmosphere or the soil, to supply much nitrogen to crops. 

 In exceptional cases, however, as in the leaf-mold of Rio 

 Cupari, examined by Boussiiigault, p. 276, as well as in 

 lands manured with fermenting dung, or with sulphate or 

 muriate of ammonia, this substance acquires importance 

 from its quantity. 



On the assumption that it is the nitrogen of these sub- 

 stances, and not their hydrogen or oxygen, which is of 

 value to the plant, we should anticipate that 17 parts of 

 ammonia would equal 54 j^arts of nitric acid in nutritive 

 effect, since each of these quantities represents the same 

 amount (14 parts) of nitrogen. The ease with which 

 ammonia and nitric acid are mutually transformed favors 

 this view, but the facts of experience in the actual feed- 

 ing of vegetation do not, as yet, admit of its acceptance. 



In earlier vegetation-experiments, wherein the nitro- 

 genous part of an artificial soil (wit) i out humus or clay) 

 consisted of ammonia-salts, it was found tliat these were 

 decidedly inferior to nitrates in their producing power. 

 This was observed by Yille in trials made Avith wheat 

 planted in calcined sand, to which was added a given 

 quantity of nitrogen in the several forms of nitrate of 

 potash, sal-ammoniac (chk)ride of ammonium), nitrate of 

 ammonia, and j^hosphate of ammonia. 



Ville's results are detailed in the following table. The 

 quantity of nitrogen added was 0.110 grm. in each case. 



Source of Nitrogen. 



Nitrate of Potas 

 Sal-aminouiae. .. 

 Nitrate of amnio 



Straw and 



Roots. JGraiii. 



( I. 20.70 6.20) 



) II. l'J.22, 7.30 \ 



i 1. 15.10 4.93) 



I II. 1' 



III. 14. S7 



Phosphate of ammonia ■ ,j" ir 'i-.i 



Average 

 crop. 



...26.71 



...18.83 

 ...18.32 



:i;g[... 18.40 



3.54 f 



Nitrogen 



in average 



crop. 



0.231 

 0.148 

 0.133 

 0.133 



