Oxide of methyl and oxide of ethyl, which are usually named methyl and ethyl ethers, are formed by mixing solutions in alcohol of methyl or ethyl iodide with sodium methoxide or ethoxide : CH₃I. Ale + NaOCH_g. Ale = NaI + H₃COCH₃.Alc. The ether has a low boiling-point, and can be separated by fractional distillation from the alcohol in which it is dissolved. Methyl ether is a gas; ethyl ether a volatile liquid, boiling at 37°. Such compounds can also be prepared more readily by distilling a mixture of the alcohol with sulphuric acid, which yields HCH₃SO₄, hydrogen methyl sulphate, with the alcohol: HCH.,SO₄ + CH₃OH = H₃COCH₃ + H₂SO₄. Now, methyl ether and hydrochloric acid combine at a low temperature, yielding ; but it is impossible to replace the chlorine by hydroxyl.

Similar sulphur compounds, however, are stable. Methyl sulphide, produced bv the action of methvl iodide on potassium sulphide, unites with methyl iodide, forminga compound containing tetrad sulphur; with silver hydroxide it yields the corresponding tri-methyl-sulphonium hydroxide,

, a compound exhibiting basic properties.

From iodine, too, iodonium compounds have been prepared, in which the iodine functions as a triad; and a hydroxide with basic properties is known.