_b._ Nitrous oxide is scarcely at all soluble in nitrous acid, and exposed to that substance, undergoes no alteration. _c._ Muriatic acid, of specific gravity 1,14 absorbs about a third of its bulk of nitrous oxide. It suffers no apparent change in its properties from being thus impregnated, and the gas is again given out from it on the application of heat. _d._ Acetic acid absorbs nearly one third of its bulk of nitrous oxide. _e._ Aqua regia, that is, the nitro-muriatic acid, absorbs a very minute portion of nitrous oxide. _f._ Nitrous oxide was exposed to a new compound acid, consisting of oxygenated muriatic acid, and sulphuric acid, which I discovered in July, 1799, and of which an account will be shortly published; but it was neither absorbed or altered. I have before mentioned that the aqueous solutions of sulphurated hydrogene and carbonic acid, neither dissolve or alter nitrous oxide. IV. _Action of Saline Solutions, and other Substances, on Nitrous Oxide._ _a._ Nitrous oxide exposed to concentrated solution of green sulphate of iron, at 58°, underwent no perceptible diminution; not even after it had been suffered to remain in contact with it for half an hour. _b._ It underwent diminution of nearly,2 when agitated in contact with a solution of red sulphate of iron, the volume of the solution being unity. _c._ Solution of green sulphate of iron, fully impregnated with nitrous gas, did not in the slightest degree absorb nitrous oxide, and appeared to have no action upon it. _d._ Solution of green muriate of iron, whether impregnated with nitrous gas, or unimpregnated, has no affinity for, or action upon, nitrous oxide. _e._ Solution of red muriate of iron in alcohol, absorbed nearly one fifth of its bulk, of nitrous oxide. _f._ Solution of prussiate of potash absorbed nearly one third of its volume, of nitrous oxide, which was again expelled from it by heat. _g._ Solution of nitrate of copper appeared to have no affinity for nitrous oxide. _h._ Concentrated solution of nitrate of ammoniac, at 58°, absorbed one eighth of its bulk of nitrous oxide. _i._ Solutions of alkaline sulphures absorb nitrous oxide in quantities proportionable to the water they contain; it is expelled from them unaltered by heat. None of the hydro-sulphures dissolve more than half their bulk of nitrous oxide. _k._ Concentrated solutions of the sulphites possess little or no action on nitrous oxide; diluted solutions absorb it in small quantities. _l._ Concentrated solution of muriate of tin absorbs about one eighth of nitrous oxide; more dilute solutions absorb larger quantities.