Phosphorus burns in it with the blue flame, probably forming with its oxygene only phosphoreous acid at the dull red heat, and with the intensely vivid flame, producing phosphoric acid at the white heat. Hydrogene, charcoal, sulphur, iron, and the compound inflammable bodies, decompose it only at heats equal to, or above, that of ignition: _probably_ each a different temperature. From the phænomena in Sect. V. it appears, that at the temperature of intense ignition, phosphorus has a stronger affinity for the oxygene of nitrous oxide than hydrogene; and reasoning from the different degrees of combustibility of the inflammable bodies, in mixtures of nitrous oxide and nitrogene, and from other phænomena, we may conclude with probability, that at about the white heat, the affinity of the combustible bodies for oxygene takes place in the following order. Phosphorus, hydrogene, charcoal,[179] iron, sulphur, &c. This order of attraction is very different from that obtaining at the red heat; in which temperature charcoal and iron have a much stronger affinity for oxygene than either phosphorus or hydrogene.[180] [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. The smallest quantity of oxygene given in the different analyses of nitrous oxide just detailed, is thirty five hundred parts; the greatest proportion is thirty-nine. Taking the mean estimations from the most accurate experiments, we may conclude that 100 grains of the known ponderable matter of nitrous oxide, consist of about 36,7 oxygene, and 63,3 nitrogene; or taking away decimals, of 37 oxygene to 63 nitrogene; which is identical with the estimation given in Research I. XV. _Observations on the combinations of Oxygene and Nitrogene._ During the decompositions of the combinations of oxygene and nitrogene by combustible bodies, a considerable momentary expansion of the acting substances, and the bodies in contact with them is generally produced, connected with increased temperature; whilst light is often generated to a great extent. Of the causes of these phænomena we are at present ignorant. Our knowledge of them must depend upon the discovery of the precise nature of heat and light, and of the laws by which they are governed. The application of general hypotheses to isolated facts can be of little utility; for this reason I shall at present forbear to enter into any discussions concerning those agents, which are imperceptible to the senses, and known only by solitary effects. Analysis and synthesis clearly prove that oxygene and nitrogene constitute the known ponderable matter of atmospheric air, nitrous oxide, nitrous gas, and nitric acid. That the oxygene and nitrogene of atmospheric air exist in chemical union, appears almost demonstrable from the following evidences.