The transparency and orange color produced in the gas that had been clouded, by new portions of it, doubtless arose from the solution of the nitric acid and water forming the cloud, in the heated nitrous vapor produced, so as to constitute an aëriform triple compound; whilst the cloudiness and absorption subsequent were produced by the diminished temperature, which destroyed the ternary combination, and separated the nitrous acid and water from the nitrous gas. From the rapidity with which the deflagration of nitrate of ammoniac proceeds, and from the immense quantity of light produced, it is reasonable to suppose that a very great increase of temperature takes place. The tube in which the decomposition has been effected, is always ignited after the process. IX. _Speculations on the decompositions of Nitrate of Ammoniac._ All the phænomena of chemistry concur in proving, that the affinity of one body, A, for another, B, is not destroyed by its combination with a third, C, but only modified; either by condensation, or expansion, or by the attraction of C for B. On this principle, the attraction of compound bodies for each other must be resolved into the reciprocal attractions of their constituents, and consequently the changes produced in them by variations of temperature explained, from the alterations produced in the attractions of those constituents. 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. [90] As is evident from the decomposition of ammoniac by heat. [91] Nitric acid is phlogisticated by heat, as appears from Dr. Priestley’s experiments. Vol. 3, p. 26. [92] As is evident from the increase of temperature required for the formation of water. 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.