Abstract: A method of producing a mono alkyl tin halide from a poly alkyl tin halide, comprising providing the poly alkyl tin halide, adding a Lewis acid catalyst to the poly alkyl tin halide to create a reaction mixture, heating the reaction mixture, dosing a hydrogen halide into the reaction mixture to convert the poly alkyl tin halide into a raw product containing mono alkyl tin halide.

Abstract: A continuous process for manufacturing foam beads using a simple apparatus, wherein the expansion agent can be easily recycled. Polymer particles and a dispersing medium are fed continuously to an unstirred mass transfer column having a high length to diameter ratio which is operated under pressure. The polymer particles and dispersing medium are subjected to thermal processing under pressure in the mass transfer column, and the resulting dispersion is sprayed into a low pressure space causing the polymer particles to expand. Accordingly, foam beads of constant quality and a uniform cell diameter and a uniform degree of expansion are manufactured without costly process means.

Abstract: A process for the manufacture of microfiltration membranes from aromatic polyamides, of which the pore sizes are between 0.05 and 10 .mu.m. A copolymer of isophthalic acid and m-phenylenediamine is dissolved in a solvent mixture of dimethylacetamide and dimethylformamide in the presence of alkali or alkaline earth chlorides and polyethyleneglycol. This solution is produced without the addition of water and is subsequently poured out onto a smooth surface formed of chemically inert material with the formation of the membranes. The water that is required as the precipitation agent, is only added to the poured-out solution by means of the air humidity. The relative air humidity is increased from 30% to 100% during formation of the membranes.

Abstract: A filter consisting of connected upper housing and lower housing parts and a hydrophobic flat filter disc for gas filtration sandwiched therebetween, intended in particular for an exchange between a container such as a liquid reservoir partially filled with liquid and the surrounding atmosphere. The upper housing part includes an integral channelled filter support having channels for communication into a gas inlet-outlet means of the said upper housing part. The lower housing part includes an integral, channelled filter support having channels for communication into a centrally disposed bore located at a right angle to the filter support and empties into the gas area of a liquid reservoir for instance. The filter support is constructed to prevent liquid from completely blocking the hydrophobic filter disc.The filter support of the lower housing forms a planar plane with an annular channel therein and a series of radially extending channels terminating at a centrally located bore.

Abstract: In a filtration apparatus for fluids and liquids having an external vessel, in particular a centrifuge tube and a filter unit disposed in the liquid, the medium to be filtered is under excess pressure and in contact with the filter element of the filter unit and for the static membrane filtration on the outer side of the filtration unit facing the vessel bottom a filter membrane is arranged with the filtration-active layer towards the outside.

Abstract: An apparatus for static membrane filtration, including a cylindrical sample vessel containing a filtration medium and subjected to centrifugal acceleration. A plunger is mounted in sealed manner in the sample vessel, and is being movable therein. An asymmetrical membrane is attached at the end of the plunger facing the bottom of the sample vessel, with the filtration active side of the membrane facing towards the outside. The bottom of the sample vessel is provided with a sealable opening. The mean density of the plunger is greater than the density of the filtration medium, and the length of the plunger in cm is greater or equal to the reciprocal of the mean plunger density in g/cm.sup.3 reduced by 1.

Abstract: A filtration or diffusion cell, consisting of adjacent facing support plates and cut diaphragm sections of a semi-permeable diaphragm, for the treating fluids. The support plates are sealed by stringlike or bandlike sealing elements for the separate flow conduction of the fluids. Support plates are provided with channel grooves, for holding the sealing elements. The channel grooves are open toward the plate plane and are provided with perforations through which a sealing material inserted in a flowable state and solidified in the grooves. Several support plates are connected by the sealing material to form a plate holder-like unit, and form seals for separate flow conduction. The support plates are square-shaped, and the front side and the back side of the cut diaphragm sections are subjected to crosswise flow of the fluid. The cut diaphragm sections are supported by grooves and groove crests extending in flow direction of the support plates.

Abstract: Incompletely condensed aldehyde resin having a large surface area and formed in the presence of large quantities of water under mild conditions is used for removing waste products, such as urea, from the blood in hemodialysis or for removing such impurities from swimming pools or aquariums.

Abstract: An asymmetrical ultrafiltration membrane based on cellulose triacetate, optionally substituted by up to 30% cellulose diacetate, is made wettable without tendency to embrittlement or shrinkage by adding hydrophobic synthetic silicic acid to the casting solution.

Abstract: An asymmetrical ultrafiltration membrane based on cellulose hydrate which may be dried without destructive shrinkage and which has been saponified without reduction in flow-through or separation performance is prepared by adding hydrophobic synthetic silicic acid to a casting solution based on cellulose triacetate optionally partially substituted by cellulose diacetate, and then casting the cellulose acetate membrane and saponifying to the cellulose hydrate form.