See Vinegar. For the methods of procuring this concentrated acetic acid, see Acidum Aceticum, Pocket Formulary. The process of the Edinburgh Pharmacopoeia yields a stronger acid than that of the London Pharmacopoeia. The acetic acid of the British Pharmacopoeia contains 28 per cent. of anhydrous acetic acid. A strong acid, very suitable for making aromatic spirit of vinegar, is procured by distilling crystallized verdigris in an earthen retort coated with clay, into a series of 3 globes, connected by opposite tubulures, and kept constantly cool, the last being furnished with a Welter's safety tube. The acid which comes over is usually coloured, and requires to be rectified by a slow and careful redistillation in a glass retort. Acetic acid of moderate strength may be rendered stronger by redistilling it over acetate of potash, rejecting the first portions that come over, and taking care that the temperature does not rise above 572° F. By redistilling it, and rejecting the first and last portions, glacial acetic acid is procured. The same acetate of potash may be used repeatedly. The process of the Dublin Pharmacopoeia yields a good product of glacial acetic acid. Acid, Carbolic. See Pocket Formulary.