between Fundi and Formiae. In 188 B.C., with Fundi, it received the full citizenship, and, like it, was to a certain extent under the control of a _praefectus_ sent from Rome, though it retained its three aediles. Mamurra was a native of Formia. Cicero possessed a favourite villa here, and was murdered in its vicinity in 43 B.C., but neither the villa nor the tomb can be identified with any certainty. It was devastated by Sextus Pompeius, and became a colony, with _duoviri_ as chief magistrates, under Hadrian. Portus Caietae (the modern Gaeta) was dependent upon it. See T. Ashby, "Dessins inedits de Carlo Labruzzi," in _Melanges de l'ecole francaise de Rome_ (1903), 410 seq. (T. As.) FORMIC ACID, H2CO2 or H.COOH, the first member of the series of aliphatic monobasic acids of the general formula CnH_(2n)O2. It is distinguished from the other members of the series by certain characteristic properties; for example, it shows an aldehydic character in reducing silver salts to metallic silver, and it does not form an acid chloride or an acid anhydride. Its nitrile (prussic acid) has an acid character, a property not possessed by the nitriles of the other members of the series; and, by the abstraction of the elements of water from the acid, carbon monoxide is produced, a reaction which finds no parallel in the higher members of the series. Finally, formic acid is, as shown by the determination of its affinity constant, a much stronger acid than the other acids of the series. It occurs naturally in red ants (Lat. _formica_), in stinging nettles, in some mineral waters, in animal secretions and in muscle. It may be prepared artificially by the oxidation of methyl alcohol and of formaldehyde; by the rapid heating of oxalic acid (J. Gay-Lussac, _Ann. chim. phys._, 1831 [2] 46, p. 218), but best by heating oxalic acid with glycerin, at a temperature of 100-110 deg. C. (M. Berthelot, _Ann._, 1856, 98, p. 139). In this reaction a glycerol ester is formed as an intermediate product, and undergoes decomposition by the water which is also produced at the same time. C3H5(OH)3 + H2C2O4 = C3H5(OH)2.OCHO+CO2 + H2O C3H5(OH)2O.CHO + H2O = C3H5(OH)3 + H2CO2.