[177] [Res. I. Div. III. S. II.]
[178] Journal de Physique, xliii. 334.
[179] As is proved by the decomposition of oxide of iron and sulphuric acid by charcoal, at that temperature.
[180] Hydrogene at or about the red heat, appears to attract oxygene stronger than phosphorus. See Dr. Priestley’s experiments, vol. i. page 262.
[181] That attraction must be called chemical, which enables bodies of different specific gravities to unite in such a manner as to produce a compound, in every part of which the constituents are found in the same proportions to each other. Atmospheric air, examined after having been at perfect rest in closed vessels, for a great length of time, contains in every part the same proportions of oxygene and nitrogene; whereas if no affinity existed between these principles, following the laws of specific gravity, they ought to separate; the oxygene forming the inferior, the nitrogene the superior stratum.
The supposition of the chemical composition of atmospheric air, has been advanced by many philosophers. The two first evidences have been often noticed.
[182] For it is unalterable by those bodies which are capable of attracting oxygene from nitrous gas and nitrous acid, at common temperatures.
[183] See the curious experiments of Rosier, Journal de Physique, 1786, vol. 1, pag. 419.
[184] As appears from the experiments of Dr. Beddoes; likewise those of Mr. Watt.
[185] As appears from the experiments of Lavoisier and Dr. Beddoes; and as will be seen hereafter.