NOTE X. (p. 247).
The Nature of the Chemical Reactions of Ammonia "Fixers."
For the student, the exact nature of the chemical reactions taking place may be of interest.
In the first place, it must be distinctly understood that the form in which ammonia escapes from the manure-heap is not, as is so commonly erroneously stated in agricultural text-books, as "free" ammonia. Whenever ammonia is brought into contact with carbonic acid, carbonate of ammonia is formed. When it is remembered that carbonic acid is by far the most abundant of the gaseous products of the decomposition of organic matter, it will be at once seen that free ammonia could not exist under such circumstances.
1. In the case of hydrochloric acid, the following chemical equation will represent the nature of the reaction—
| 2HCl | (NH4)2CO3 | 2NH4Cl | H2O+CO2 | |||
| (Hydrochloric | + | (carbonate of | = | (sal-ammoniac,) | + | (carbonic acid.) |
| acid,) | ammonia,) |
2. In the case of sulphuric acid, the equation will be—
| H2SO4 | (NH4)2CO3 | (NH4)2SO4 | H2O+CO2 | |||
| (Sulphuric acid,) | + | (carbonate of | = | (sulphate of | + | (carbonic acid.) |
| ammonia,) | ammonia,) |
3. With gypsum (CaSO4)—
| CaSO4 | (NH4)2CO3 | CaCO3 | (NH4)2SO4 | |||
| (Gypsum,) | + | (carbonate of | = | (calcium | + | (sulphate of |
| ammonia,) | carbonate,) | ammonia.) |