I now introduced about half a cubic inch of pyrophorus to two cubic inches of nitrous gas; the combustion took place, and the gas was rapidly diminished to one half; and on suffering it to remain five minutes to one third nearly; which extinguished flame. Suspecting that this great diminution was owing to the absorption of some of the nitrogene formed, by the charcoal of the pyrophorus, I carefully made a quantity of pyrophorus; employing more than two thirds of alumn, to one third of sugar. To rather more than half of a cubic inch of this, two cubic inches of nitrous gas, which contained about ¹/₄₀ nitrogene, were admitted. After the combustion, the gas remaining, _apparently_ filled a space equal to 1,2 cubic inches; but, as on account of the burnt pyrophyrus in the jar, it was impossible to ascertain the volume with nicety, it was carefully and wholly transferred into another jar. It filled a space equal to 1,15 cubic inches nearly. When water was admitted to this gas no absorption took place. It underwent no diminution with nitrous gas, and a taper plunged into it was instantly extinguished. We may consequently conclude that it was nitrogene. Now 2 cubic inches of nitrous gas weigh,686 grains, and 1,1 of nitrogene—,05, the quantity previously contained in the gas = to 1,05, 3,19. Hence,686 of nitrous gas would be composed of,367 oxygene, and ,319 nitrogene; and 100 grains would contain 53,4 oxygene, and 46,6 nitrogene. IV. _Additional observations on the combustion of bodies in Nitrous Gas, and on its Composition._ Though phosphorus may be fused, and even sublimed, in nitrous gas, without producing the slightest luminous appearance,[103] yet when it is introduced into it in a state of active inflammation, it burns with almost as much vividness as in oxygene.[104] Hence it is evident, that at the heat of ignition, phosphorus is capable of attracting the oxygene from the nitrogene of nitrous gas. [103] No luminous appearance is produced when phosphorus is introduced into _pure_ nitrous gas. It has been often observed, that phosphorus is luminous in nitrous gas, that has not been long in contact with water after its production. This phænomenon, I suspect, depends either on the decomposition of the nitric acid held in solution by the nitrous gas; or on the combination of the phosphorus with oxygene loosely adhering to the binary aëriform compound of nitric acid and nitrous gas. I have not yet examined if nitrous gas can be converted into nitrous oxide by long exposure to heated phosphorus: it appears, however, very probable. [104] Perhaps this fact has been noticed before; I have not, however, met with it in any chemical work.