Abstract: The invention proposes using liquefied carbon dioxide as a separation agent for flotation and/or sedimentation separation, which is particularly suitable for separating foodstuff mixtures such as meat components, because it can be maintained in liquid phase at the freezing point of water and is inert with respect to many substances of the mixture. By controlling the pressure and/or the temperature at values of about 26 bar and -14.degree. C., the density of the separation agent can be adjusted to correspond to that of water so that water containing substances of the mixture can be readily separated.

Abstract: An instrument for determining visual surface properties includes a generally cylindrical housing 10 with an illumination unit 12 and a photo cell 22 disposed in its upper portion. The beam A emitted by the illumination unit 12 passes through an optical system 19 disposed in a lower portion of the housing 10 and is directed by a first prism 20 at a predetermined angle onto the surface 11 under examination. The beam A' reflected at a predetermined angle by the surface 11 is deflected by a second prism 20', passes the same optical system 19 a second time and is received by the photo cell 22. A plurality of pairs of prisms with different angles of incidence and reflection are arranged concentrically about the central axis N of the housing 10. An inexpensive instrument is thus achieved which is small in the direction parallel to the surface under examination.

Abstract: A honing or grinding tool and a measuring device used therewith is descri The honing tool includes a cutting element, a cutting element support and a layer disposed between and connecting the cutting element and the cutting element support. The layer includes a substance embedded therein which selectively absorbs and/or emits electromagnetic radiation at specific wavelengths, such that the substance is exposed when the cutting element is worn off and detected by the measuring device.

Abstract: The invention relates to a device for use in chromatometry of samples, viz. olored surfaces, by measurement of reflectance. It comprises a testing head having a measuring cell and a measuring surface. The measuring cell is provided in each of five radial planes with three optical fibre bundles for irradiation of the sample, said optical fibre bundles being disposed at three different angles of e.g. 15.degree., 30.degree. and 70.degree. to the measuring surface. In the center at the top of the measuring cell there is also provided an optical fibre bundle oriented perpendicular to the measuring surface and intended to divert the radiation reflected from the sample. According to the invention a switching system is provided which permits selectively to turn on or off a part of the total number of optical light guide means, especially in accordance with a plurality of preselectable programmes.