Alcohol Methylicum.—Methyl Alcohol.
FORMULA: CH3OH. MOLECULAR WEIGHT: 31.93.
SYNONYMS: Wood alcohol, Wood naphtha, Pyroxylic spirit (or alcohol), Pyroligneous spirit (or alcohol), Spiritus pyroxylicus rectificatus.
Preparation and History.—This substance was first carefully studied and named by Dumas and Peligot (1834), though previously differentiated from ethyl alcohol by Philip Taylor, in 1812, and noticed still earlier by Boyle, in 1661. As a result of the destructive distillation of wood, several substances are obtained (as noticed under Acetic Acid), among them 1 per cent of crude pyroxylic spirit. When calcium carbonate is added to the aqueous liquor containing the crude product, the salt calcium acetate is formed, and upon distilling the solution, that portion passing over before a temperature of 100° C. (212° F.) is reached, contains the crude wood alcohol. The next step is its purification, which is accomplished by saturating it with fused chloride of lime, forming thereby, with the crude spirit, a crystalline body, which is then distilled to allow impurities to pass over. To separate the pyroxylic spirit from the calcium compound, water is added, and the mixture again distilled, after which it is freed from the water by being left in contact with dry lime, and rectified.
Description and Tests.—Anhydrous methyl alcohol, when pure, is a limpid liquid, colorless, has a pungent, burning taste, and a peculiar odor, somewhat like that of acetic ether and alcohol. Like alcohol, it burns with a pale-blue, though less luminous, flame. Alcohol, ether, and water dissolve it in all proportions, and its solvent properties are said to be the same as those of alcohol. It may be distinguished from acetone by its power of dissolving calcium chloride. It should be free from a smoky odor. Its boiling point is about 67° C. (152.6° F.), and it has a specific gravity of 0.8021 at 15.5° C. (60° F.). Its vapor occasions conjunctival irritation. Crude pyroxylic spirit is used largely in the arts and especially as a solvent for resins in the manufacture of varnishes. The methylated spirit of Great Britain is a mixture of alcohol, 8/9 parts, and pyroxylic spirit, 1/9 part. It is employed in laboratories in making ether, nitrous ether, and chloroform, and is used in the arts as well, for its solvent properties and on account of being cheaper than ethyl alcohol, the duty on which is heavy, unless to be used in the arts; then the duty is removed by the Government. But in this case the ethyl alcohol must be mixed with wood-spirit, so as to render it unfit for use in beverages.
At present, an important use of wood alcohol is for the production of formaldehyde (see Formaldehydum). Wood alcohol should not become colored by exposure to the air and light. It mixes with water in all proportions, without becoming muddy, and when pure has no action on paper stained with vegetable colors. It may be preserved without alteration in a vessel, though imperfectly corked; but when its vapor, mixed with air, is left in contact with spongy platinum, much heat is evolved, and formic acid is formed. It dissolves many salts, many resins, hydroxides of potassium and sodium, most essential oils, and forms crystalline compounds with chloride of calcium, barium oxide, and lime. The admixture of ethyl alcohol is recognized by the fact that concentrated sulphuric acid will, upon warming, liberate ethylene gas. In the absence of ethyl alcohol, the presence of acetone may be shown by its capacity of yielding iodoform upon warming with iodine and sodium carbonate.
Action, Medical Uses, and Dosage.—The fumes of wood spirit occasion conjunctival irritation, nausea, anorexia, headache, and vertigo. It was the reparation recommended by Dr. J. Hastings as a remedy for phthisis pulmonalis; he incorrectly termed it Wood naphtha. Although it has no influence in effecting cures in this disease, it is frequently of service in relieving the cough and feverish symptoms which manifest themselves. As to its action in vomiting, Christison says, "I can amply confirm all that has been said of it as an antiemetic remedy in cases of chronic vomiting; for in cases of this affection, depending on both functional or organic disease, I have frequently seen the vomiting arrested, or greatly mitigated, by pyroxylic spirit." It has also been found of service in dysentery and diarrhoea, dyspepsia, catarrhal disorders, and for the expulsion of intestinal worms. The dose is from 5 to 20 drops, 3 or 4 times a day, mixed with a fluid drachm or two of compound tincture of cardamom and a fluid ounce of water. It may be substituted for alcohol in lamps for chemical purposes, and answers exceedingly well for making varnishes, as it is more volatile than alcohol. Bodies which contain much oxygen, are more readily dissolved by it than hydrogenous bodies. It has now been practically abandoned as a medicine.