Abstract: In a laser-optical arrangement for producing signals by light scattering, obscuration or reflection, from flowing particles and/or groups of particles, which are recorded, as time-dependent voltage/current fluctuations, by means of a photodetector (9) via appropriate imaging optics (7,8,18), assignment to the degree of dispersion of the flowing system is based on a subsequent measurement (10) of the root-mean-square value, and, according to the invention, the sample stream (1) is separated from a transmitter (6,7,18) and a receiver (8,9,10) by an enveloping stream (4), and the transmitter side consists of an individual light-transmitting fiber (7) provided with a means for parallel or focused emergence of a light bundle having a diameter of the order of magnitude of the particles and/or groups of particles.

Abstract: Pyrocatechol methylcarbamate is prepared by reacting pyrocatechol carbonate with methylamine in the presence of a tertiary amine and, preferably, a solvent.

Abstract: Finely divided, pulverulent carotinoid or retinoid compositions, in which the carotinoid or retinoid essentially has a particle size of less than 0.5 micron, are prepared by a process wherein a carotinoid or retinoid is dissolved in a volatile, water-miscible, organic solvent at from 50.degree. C. to 200.degree. C., if necessary under superatmospheric pressure, within the space of less than 10 seconds. The carotinoid is immediately precipitated, in a colloidally disperse form, from the molecularly disperse solution by rapidly mixing the latter with an aqueous solution of a swellable colloid at from 0.degree. C. to 50.degree. C., and the resulting dispersion is freed from the solvent and the dispersing medium in a conventional manner.

Abstract: The use of a dye of the general formula I ##STR1## where R is a heterocyclic radical, X is hydrogen, nitro, or unsubstituted or substituted amino, hydroxyl or mercapto and Y is hydrogen, nitro, or unsubstituted or substituted amino, hydroxyl or mercapto, and the ring A can be additionally substituted, in an electro-optical display containing liquid crystals, and a liquid-crystal mixture containing a dye of the general formula in claim 1.

Abstract: Azo dyes which in the form of the free bases correspond to the general formula ##STR1## where R.sup.1 is hydrogen, chlorine, bromine, methyl, trifluoromethyl, methoxy, nitro or a radical X, R.sup.2 is hydrogen, chlorine or nitro, R.sup.3 is hydrogen, chlorine, bromine, methyl, methoxy, nitro or a radical X, R.sup.4 is hydrogen or alkyl of 1 to 3 carbon atoms, R.sup.5 is cyano, carbamoyl or acetyl, R.sup.6 is hydrogen, substituted or unsubstituted alkyl or cycloalkyl or a radical X and X is a radical containing an amino group, the molecule containing at least one radical X. The compounds of the formula I are exceptionally useful for improving the flow of pigment-containing printing inks.