Thus in nitrate of ammoniac, four affinities may be supposed to exist:
1. That of hydrogene for nitrogene, producing ammoniac.
2. That of oxygene for nitrous gas, producing nitric acid.
3. That of the hydrogene of ammoniac for the oxygene of nitric acid.
4. That of the nitrogene of ammoniac for the nitrous gas of nitric acid.
At temperatures below 300°, the salt, from the equilibrium between these affinities, preserves its existence.
Now when its temperature is raised to 400°, the attractions of hydrogene for nitrogene,[90] and of nitrous gas for oxygene,[91] are diminished; whilst the attraction of hydrogene for oxygene[92] is increased; and perhaps that of nitrogene for nitrous gas.
Hence the former equilibrium of affinity is destroyed, and a new one produced.
The hydrogene of the ammoniac combines with the oxygene of the nitric acid to generate water; and the nitrogene of the ammoniac enters into combination with the nitrous gas to form nitrous oxide: and the water and nitrous oxide produced, most probably exist in binary combination in the aëriform state, at the temperature of the decomposition.
But when a heat above 800° is applied to nitrate of ammoniac, the attractions of nitrogene and hydrogene for each other, and of oxygene for nitrous gas,[93] are still more diminished; whilst that of nitrogene for nitrous gas is destroyed, and that of hydrogene for oxygene increased to a great extent: likewise a new attraction takes place; that of nitrous gas for nitric acid, to form nitrous vapor.[94] Hence a new arrangement of principles is rapidly produced; the nitrogene of ammoniac having no affinity for any of the single principles at this temperature, enters into no binary compound: the oxygene of the nitric acid forms water with the hydrogene, and the nitrous gas combines with the nitric acid to form nitrous vapor. All these substances most probably exist in combination at the temperature of their production; and at a lower temperature, assume the forms of nitrous acid, nitrous gas, nitrogene, and water.