Abstract: Cyclohexane-1,3-diones of the formula ##STR1## having up to 24 carbon atoms are prepared in admixture with 6-alkyl-3,4-dihydro-2-pyranones of the formula ##STR2## having up to 24 carbon atoms, in which formulae the radicals R and R' may be identical or different and represent each a hydrogen atom, an alkyl, a cycloalkyl or an aryl group each having up to 12 carbon atoms and the two radicals R' together optionally represent a --(CH.sub.2).sub.3 -group, by passing 4-oxocarboxylic acids of the formula ##STR3## having up to 24 carbon atoms and in which R and R' have the above meaning at a temperature of from 250.degree. to 500.degree. C in the gaseous phase over a dehydration catalyst and the pyranones are converted into cyclohexane-1,3-diones by passing them in the gaseous phase over a dehydration catalyst at a temperature of from 250.degree. to 500.degree. C.

Abstract: An apparatus for controlling a photogrammetrical camera includes a frosted glass adjacent to which or in an optically conjugate plane thereto a transparent planoparallel sheet of voltage sensitive material is arranged. Spaced electrodes are allocated to the one face of said sheet and a sheet electrode to the other face. Each of the spaced electrodes is connected to respective outputs of an electronic counter, which in dependence of a tunable pulse generator applies voltage pulses to the spaced electrodes and the sheet electrode, both sandwiching said sheet of voltage sensitive material and rendering visible the inbetween portions of said material when submitted to a potential so that lines or a cyclic pattern of lines appear. The voltage sensitive material can be liquid or gaseous or solid and can be sandwiched between two substantially plano-parallel plates which have the respective electrodes or electrode on their inner faces.

Abstract: Cyclohexanediones-1,3 are prepared in a good selectivity by reacting an .alpha.,.beta.-unsaturate carboxylic acid ester with a ketone in the liquid phase in the presence of a strong base and a solvent selected from the group consisting of carboxylic acid amides, phosphoric acid amides, sulfoxides, sulfones, and glycol dialkyl ethers.

Abstract: The present invention is related to a process for the manufacture of hydroquinone by catalytic dehydrogenation of cyclohexanedione-(1,4) in the liquid phase by means of a dehydrogenation mixture composed of a solvent and a catalyst comprising a noble metal of Group VIII of the periodical system.

Abstract: Process for preparing resorcinols from .delta.-ketocarboxylic acids or their lactones in the gaseous phase at temperatures from 150.degree.14 500.degree. C by means of a dehydrogenation catalyst.

Abstract: A two step process for concentrating and desalting dilute sulfuric acid including, first indirectly countercurrently contacting and heating the dilute acid with steam from a second step, removing overhead water vapor and withdrawing concentrated acid, and second further concentrating the acid by directly countercurrently contacting and heating the acid with superheated steam, removing overhead steam and additional water vapor, which is used in the first heating step. Acid of a higher concentration is withdrawn and cooled to crystallize and remove salts and the more highly concentrated sulphuric acid recovered.