The nitrous gas in contact with tin had undergone a diminution of one fourth only, and did not support flame. VI. _Miscellaneous Observations on the conversion of Nitrous Gas into Nitrous Oxide._ _a._ Dr. Priestley found nitrous gas exposed to a mixture of iron filings and sulphur, with water, converted after a certain time, into nitrous oxide. Sulphurated hydrogene is always produced during the combination of iron and sulphur, when they are in contact with water; and by the hydrogene of this in the nascent state, the nitrous gas is most probably decomposed. _b._ Green oxide of iron moistened with water, exposed to nitrous gas, slowly gains an orange tinge, whilst the gas is diminished. Most likely it is converted into nitrous oxide; but this I have not ascertained. _c._ I exposed nitrous gas, to the following bodies over mercury for many days, without any diminution, or apparent change in its properties. Alcohol, saccharine matter, hydrocarbonate, sulphureous acid, and phosphorus. _d._ Crystalised sulphate, and muriate of iron, absorb a small quantity of nitrous gas, and become dark colored on the outside; but after this absorption, (which probably depends on their water of crystalisation,) has taken place, no change is effected in the gas remaining. _e._ The power of iron to decompose water being much increased by increase of temperature, nitrous gas is converted into nitrous oxide much more rapidly when placed in contact with a surface of heated iron, than when exposed to it at common temperatures. During the decomposition of nitrous gas in this way, ammoniac[140] is formed. _f._ The curious experiments of Rouppe,[141] on the absorption of gases by charcoal, compared with the phænomena noticed in this Division, render it probable that hydrogene in a state of loose combination with charcoal, will be found to convert nitrous gas into nitrous oxide. [140] As was observed by Milner. Nitrous gas passed over heated zinc, or tin, I doubt not will be found converted into nitrous oxide. [141] Annales de Chimie, xxxii. p. 3. VII. _Recapitulation of conclusions concerning the conversion of Nitrous Gas into Nitrous Oxide._ _a._ Certain bodies having a strong affinity for oxygene, as the sulphites, dry sulphures, muriate of tin, &c. convert nitrous gas into nitrous oxide, by simply attracting a portion of its oxygene; whilst the remaining oxygene enters into combination with the nitrogene, and they assume a more condensed state of existence. _b._ Nitrous gas is converted into nitrous oxide by hydrogene, in a peculiar state of existence, as in sulphurated hydrogene; and that by a series of very complex affinities. Both oxygene and nitrogene are attracted from the nitrous gas by the hydrogene, in such proportions as to form water and ammoniac, whilst the remaining oxygene and nitrogene[142] assume the form of nitrous oxide.