Acetic acid is the second simplest carboxylic acid (after formic acid). Vapors of formic acid and acetic acid are the most commonly used. Ammonium formate first dissociates into formic acid and ammonia. Industrially, formic acid is produced from methanol. Calcium formate is the calcium salt of formic acid. It can exist in three forms&colon; gossypol, gossypol acetic acid, and gossypol formic acid. Treatment of formic acid with sulfuric acid is a convenient laboratory source of CO. Methyl formate is used primarily to manufacture formamide, dimethylformamide, and formic acid. Side-products may also form, including butanone, ethyl acetate, formic acid, and propionic acid. Liquid formic acid tends to supercool. Many form spontaneously when alcohols dissolve in formic acid. It is readily oxidized by atmospheric oxygen into formic acid. Acids such as trifluoroacetic acid and formic acid may be used for cleavage. Esters, salts, and the anion derived from formic acid are called formates. The conjugate base of formic acid, formate, also occurs widely in nature.