Into a capacious distilling apparatus connected with the cooling pipe, so that the distillate constantly flows back, bring 1 part, by weight, of glycerin of the consistency of syrup, add ¼ of its weight of crystallized oxalic acid and the same quantity of alcohol of 90 to 95 per cent. With moderate heating a vigorous development of gas soon takes place. The oxalic acid in contact with the glycerin splits into formic acid and carbonic acid, according to the following equation:-- {COOH = CHO.OH + CO_{2}. {COOH └--┬--┘ └----┬----┘ └--┬--┘ Oxalic acid. Formic acid. Carbonic acid. The glycerine does not undergo alteration thereby. The nascent formic acid converts the alcohol present into formic ether, water being separated. When, after continued heating, the development of carbonic acid abates, add the same quantities of oxalic acid and alcohol to the contents of the still, heat again until but little carbonic acid is evolved, and then add, twice in succession, the same quantities of oxalic acid and alcohol as before, until finally as much oxalic acid is consumed as glycerin has been employed. When the evolution of carbonic acid ceases, the receiver is reversed and the ether distilled off. The glycerin remaining behind is again concentrated to the consistency of syrup, and may be re-used. The distillate is freed from free acid by the addition of magnesia, and the alcohol and water are separated by shaking with calcium chloride, after which the pure ether is obtained by rectification. Formic ether is colorless, thinly-fluid, of a pleasant smell, specific gravity 0.945, boiling point 130° F., soluble in cold water, and miscible in every proportion with alcohol and ether.