Abstract: Process and structure for etching copper, as in the manufacture of printed circuit boards. The copper is exposed to a gaseous or liquid oxidant in the presence of a catalyst which promotes the reaction of copper with the oxidant. In some embodiments, the catalyst is carried by a medium which also serves as a receiver for oxidized copper species produced by the reaction, and in one preferred embodiment, the medium comprises a laminated structure having a first layer which contains a catalyst and a second layer which receives the oxidized copper species. The etching is substantially anisotropic, which alleviates the problem of undercutting.

Abstract: A solar heating collector is employed in the form of a plenum constituted of the greenhouse translucent roof and a roof floor of black plastic sheeting. Hot air from the plenum is distributed by air directing means to a heat storage chamber in a charge cycle or directly to the greenhouse in a direct heat cycle. In a discharge cycle air from the greenhouse is directed through the heat storage chamber to be heated and discharged into the greenhouse. Specially designed collapsible tubes are employed in the system for distribution of exhaust air and distribution of heated air from a manifold. The heat storage chamber employs cylindrical containers of a phase change material to store solar energy and serves to support the air directing means and the aforementioned collapsible tubes to provide a central unit for providing and monitoring solar heat distribution.

Abstract: A thermal energy storage device and method for making the same. The thermal energy storage device is in the form of a sealed tube-like container such as a tube-like cylinder or other geometrical configuration partially filled with a phase change material such as calcium chloride hexahydrate. The cylinder is made of tubular high density polyethylene and more particularly an ultra high molecular weight high density polyethylene having a molecular weight of about 500,000 to 700,000 which is tough, chemically resistant, withstands low and high temperatures, acts as a moisture vapor barrier and can be fused and sealed. The calcium hexahydrate is filled in an open top cylinder, closed at the bottom by dissolving two parts of calcium chloride dihydrate with one part of water to provide calcium chloride hexahydrate in liquid form. The cylinder is filled to about 90% by volume and a cap of the same material is then preheated to about fusion temperature.

Abstract: A self-centering trailer hitch includes a housing intended to be secured to either a tractor or trailer, with a guide tube laterally pivotally supported on the housing, an extensible and retractable tongue is telescoped into the tube, cooperable cam wedges and rollers on the housing and tongue urge the tongue and tube to a centered towing position as the tractor is backed toward the trailer, and detent means automatically lock the tube and the tongue in centered towing positions. The tongue may also be centered and locked for towing following connection of the hitch by moving the tractor ahead to align the tongue with the centerline of the vehicles and then backing the tractor toward the trailer until the detent locks the parts together.

Abstract: The present invention is a method for making an electrically insulative coupling which is inserted between and coupled to two lengths of metallic pipe. The method comprises the steps of machining one end of two short sections of metallic pipe to provide a circumferential groove, inserting O rings onto the grooves, inserting the machined ends of the pipe sections into a central sleeve, injection moulding an outer insulative sleeve over the machined pipe ends and central sleeve, and pressing a metal outer sleeve over the outer insulative sleeve. By this method the electrically insulative coupling is manufactured quickly and inexpensively.