Novel 2:3:4:5 - tetrahydro - 1:4 - methano 1H-3-benzazepines of formula <FORM:1078849/C2/1> which are in the 1-position unsubstituted or substituted by a lower alkyl group or by an aralkyl or aryl group, in the 3-position unsubstituted or substituted by an alkyl, alkenyl, aryl or aralkyl group, or a cycloalkyl or cycloalkyl alkyl group, are unsubstituted in the 4-position, contain in the 5-position an oxo group or two hydrogen atoms, or one hydrogen atom together with a free, etherified or esterified hydroxyl group, or an alkyl aralkyl, or aryl group together with a free, etherified or acylated hydroxyl group, contain in the 2-position an oxo group or, if there is no oxo group in the 5-position, may also be unsubstituted in the 2-position, and in the 6, 7, 8, and 9 positions are unsubstituted or substituted by one or more substituents selected from lower alkyl groups, lower alkoxy groups, hydroxyl groups, acyloxy groups, halogen atoms and trifluoromethyl groups, the term lower herein meaning those groups containing up to seven carbon atoms, and a process for their manufacture wherein an N-Rx-1-R-4-oxo-1:2:3:4-tetrahydronaphthalene-1-carboxylic acid amide in which Rx represents a hydrogen atom, or a hydrocarbon group which may be substituted and R represents a hydrogen atom, or a hydrocarbon group which may be substituted, and which contain a halogen atom at the 3-position, and whose amide nitrogen atom carries at least one hydrogen atom, is condensed intra-molecularly and, if desired, substituents is/are introduced into the compounds so obtained or substituents in the said compound are modified or split off.  The condensation is advantageously carried out in the presence of a strong base and with solvents or diluents.  The compounds contain an asymmetric carbon atom in the 5-position and racemate mixtures may be separated in a known manner into the optical isomers.  1 - Ethyl - 3 - isopropylidene - 5b  - hydroxy - 2:3:4:5 - tetrahydro - 1:4 - methano - 1H - 3 - benzazepinium-methane sulphonate is prepared by treatment of a solution of the corresponding free base in acetone with a small excess of methane sulphonic acid.  N - Rx - 1R - 3 - halo - 4 - oxo - 1:2:3:4 - tetrahydronaphthalene - 1 - carboxylic acid amides wherein Rx and R have the above significance are prepared by halogenating the corresponding 3-unsubstituted compound.  1 - Phenyl - 4 - oxo - 1,2,3,4 - tetrahydronaphthalene - 1 - carboxylic acid amide is prepared by reacting diphenylacetonitrile and acrylic acid ethyl ester in the presence of triethylbenzylammonium hydroxide, treating the resulting g  - g  - diphenyl - g  - cyano - butyric acid ethyl ester with methanolic sodium hydroxide, and treating the resulting g -g -diphenyl-g -cyanobutyric acid with sulphuric acid.  1 - Ethyl - 4 - oxo - 1:2:3:4 - tetrahydronaphthalene - 1 - carboxylic acid - n - butylamine and anilide are prepared by boiling 1-ethyl-4-oxo - 1:2:3:4 - tetrahydronaphthalene 1 - carboxylic acid amide with glacial acetic acid and concentrated HCl to form the corresponding free carboxylic acid, treating this acid with PCl5 and reacting the resulting carboxylic acid chloride with n-butylamine and aniline respectively.  Pharmaceutical compositions having diuretic, analgesic and hypotensive effect may be administered enterally, parenterally, or topically, in the form of tablets, dragees, capsules, salves or creams, or in liquid form as suspensions, solutions or emulsions, or may be in the form of animal feedstuffs or additives to animal feedstuffs and contain a compound of the first general formula above as the active ingredient.