An apparatus for the manufacture of selectively apertured thermoplastic sheet or film, comprising a rotatable molding element means for receiving the film and which means has a predetermined pattern therein wherein as the film is contacted with the rotatable molding element means and a fluid pressure differential is applied to the surface of the film, a desired pattern of perforated areas and non-perforated areas are imparted to the film with each of said areas being continuous across the web of the film and alternating in the machine direction.

The cell voltage of an electrolytic cell having an anode compartment separated from a cathode compartment, the cathode compartment containing an alkaline catholyte solution is reduced in a method which comprises introducing into the cathode compartment a compound of a heavy metal selected from Groups IVB, VB, and VIB and an alkylene polyamino complex with cobalt or iron. The method results in significant cell voltage reductions in electrolytic cells employing as separators porous diaphragms or ion exchange membranes.

A method of using an elongated, generally vertically extending cocurrent reactor vessel for the production of hypochlorous acid by the mixing and reaction of a liquid alkali metal hydroxide and a gaseous halogen is provided wherein an atomizer is mounted near the top of the reactor vessel to atomize the liquid alkali metal hydroxide into droplets in the vessel. The vessel has a spraying and reaction zone immediately beneath the atomizer and a drying zone beneath the spraying and reaction zone to produce a gaseous hypochlorous acid and a substantially dry solid salt by-product.

A laminated, cylindrical, metal screen or molding element for vacuum perforation of plastic film or sheets, comprising two or more relatively thin cylindrical metal screens, each having a predetermined inside and outside diameter and each having a plurality of openings or holes therein of a predetermined size and geometrical shape, and said relatively thin screens stacked and bonded together, diametrically one inside the other thereby providing a screen of a desired thickness and a desired hole geometry wherein the holes in the screen have substantially straight walls perpendicular to the surface of the screen. A method of producing a relatively thick cylindrical metal screen for vacuum perforation of plastic film or sheets wherein the holes or openings in the screen have substantially straight walls perpendicular to the surface of the screen, comprising stacking and bonding together two or more matched relatively thin metal screens diametrically one inside the other.

A laminated, cylindrical, metal screen or molding element for vacuum perforation of plastic film or sheets, comprising two or more relatively thin cylindrical metal screens, each having a predetermined inside and outside diameter and each having a plurality of openings or holes therein of a predetermined size and geometrical shape, and said relatively thin screens stacked and bonded together, diametrically one inside the other thereby providing a screen of a desired thickness and a desired hole geometry wherein the holes in the screen have substantially straight walls perpendicular to the surface of the screen.；A method of producing a relatively thick cylindrical metal screen for

There is disclosed an adapter apparatus for permitting a trailer or similar vehicle intended to be towed from a rear-mounted ball hitch on a truck to rather be coupled to and towed by a truck having a fifth wheel type hitch. The apparatus includes a gooseneck with a kingpin adapted to engage the fifth wheel mount of a truck, a gooseneck mounting element for receiving the gooseneck in a horizontally adjustable manner and two upright columns which are rigidly secured to the tongue of the trailer on either side of the ball hitch and on which the mounting element is slidably attached. The columns and the gooseneck arm are of steel with rectangular cross-section and slidably engage respectively in steel box-beam portions of the mounting element. Each column and the arm include holes which selectively match a pair of holes in the mounting element. A pair of pin elements secure the mounting element against relatively sliding movement. The pin elements may be secured in place by padlocks for security against theft.

An elongated, generally vertically extending cocurrent reactor vessel for the production of hypochlorous acid by the mixing and reaction of a liquid alkali metal hydroxide and a gaseous halogen is provided wherein a nozzle is mounted near the top of the reactor vessel beneath the gas injector to spray the liquid alkali metal hydroxide in droplets so that the halogen gas can be absorbed into the surface of the droplets simultaneously with water evaporation in the vessel. The vessel has a spraying and reaction zone immediately beneath the atomizer and a drying zone beneath the spraying and reaction zone.