Abstract: Polymers of tetrafluoroethylene are produced by suspension polymerization in the presence of small amounts of definite perfluorinated ethers. The products obtained have improved processing properties.

Abstract: Modified tetrafluoroethylene dispersion polymers are prepared by polymerizing tetrafluoroethylene in the presence of perfluorinated vinyl ethers of the formula I ##STR1## as modification agent. The articles made from the polymers by paste-extrusion have improved mechanical and electrical properties even if the extrusion is carried out at a high reduction ratio and draw-off rate.

Abstract: Secondary radiation in a non-linear crystal is produced by irradiating the crystal with a coherent primary radiation, to produce a coherent phase-adapted secondary radiation whose frequency is doubled with respect to the frequency of the primary radiation. In a modification of the method, two different sources of primary radiation are used, in such a way that the secondary radiation in the crystal is equal to the sum or the difference of the frequencies of the primary radiation sources. In apparatus for carrying out the method, the crystal to be irradiated is mounted in a swinging or tiltable carrier. The emerging radiation is partially reflected onto a pair of photoelectric detectors, the output of which controls a servomotor to vary the degree of tilt of the crystal. In a second embodiment, there are two crystals tilting in opposite directions. In a third embodiment of the apparatus, two separate sources of primary radiation serve to irradiate a single crystal.

Abstract: Samples of fine dusts in air or gases are collected for analysis and measurement by atomic absorption or atomic fluorescence by conducting the air or gases across a surface of a sample container and causing the dust to be deposited electrostatically on the said surface. The sample container is then heated to a temperature sufficient to vaporize the particles of dust, and the vaporized particles are then brought into the beam path of an atomic absorption or atomic fluorescence spectrometer.

Abstract: Fluorocarbon wax dispersions are produced by telomerization of tetrafluoro-ethylene or mixtures of tetrafluoro-ethylene with other olefinic monomers. The stable wax dispersions and the pulverulent fluorocarbon waxes obtained are, inter alia, valuable additives for lubricants and polishes.