VALUE OF AMMONIA AND NITRIC ACID. 301 
been similarly made out. We 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 Boussingault, 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 parts 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 vegctation-experiments, wherein the nitro- 
genous part of an artificial soil (without humus or clay) 
consisted of ammonia-salts, it was found that these were 
decidedly inferior to nitrates in their producing power. 
This was observed by Ville in trials made with wheat 
planted in calcined sand, to which was added a given 
‘ quantity of nitrogen in the several forms of nitrate of 
potash, sal-ammoniac (chloride of ammonium), nitrate of 
ammonia, and phosphate of ammonia. 
Ville’s results are detailed in the following table. The 
quantity of nitrogen added was 0.110 grm. in each case. 
Nitrogen 
Straw and Average jin average 
Source of Nitrogen. Roots. |Grain.| crop. crop. 
I. 70) 6.2 
Nitrate of Potash.......s.sss005 tor 19.2 es t 2.26.71} 0.221 
| Salamthonine......sseeeeeeess § i tae 2-231 |. .18.83] 0.148 
Nitrate of ammonia,........e++- noe 588 L 18.82] 0.188 
Phosphate of ammonia.........- 4 ye RB 88] 3-27 | ..18.40| 0.188 
