Methyl is an organic radical homologous with Ethyl (q.v.). Its formula is CH3, but, as it cannot exist in the free state, two such groups of atoms unite together to form ethane, CH3—CH3. As in the case of ethyl, methyl is the centre of a whole group of substances known as the methyl-group. Thus, the hydride of methyl, CH3H, known as light carburetted hydrogen, marsh-gas, or fire-damp, is well known as the cause of explosions in coal-mines. It is a light, inodorous gas, half as heavy as air; non-poisonous and very inflammable, forming an explosive mixture with seven volumes of air. Methyl alcohol, CH3OH, is obtained as a by-product in the manufacture of beet-root sugar, and also by the dry distillation of wood. It is a colourless, mobile liquid, resembling ordinary alcohol in many of its properties. Methyl oxide or methyl ether, (CH3)2O, corresponding to ethyl ether or common ether, is a gas at ordinary temperatures, very soluble in water and alcohol, and capable of being condensed to a liquid by pressure and cold. It is largely prepared for use in freezing-machines, owing to the intense cold which results when the liquefied gas is allowed to evaporate. It is prepared by the action of sulphuric acid on wood spirit.
Besides the above, methyl enters into the constitution of many ethereal salts and amines, such as methyl chloride, acetate, and salicylate, as well as methyl amine, dimethyl amine, &c. (see AMINES). The salicylate, , is interesting as being the ethereal oil of Gaultheria procumbens, from which pure methyl alcohol and pure salicylic acid can both be made. For Methyl Violet, see DYEING; and for Methylene, see ANÆSTHESIA.