Abstract: A thin-film heating element is formed of a temperature-stable, electrically insulating substrate having a thin, electrically conductive metal oxide film which is doped with foreign atoms which compensate each other in pairs and which each consist of at least one acceptor-forming element and one donor-forming element the metal oxide film being provided with connecting electrodes; the metal oxide film being doped with maximally 10% of each of the foreign atoms compensating each other in pairs, the quantity of the atoms differing maximally 10%.

Abstract: An electrodeless low-pressure gas discharge lamp includes a glass lamp vessel (1) which is provided with a sealing member (6) connected to the wall of the lamp vessel by means of a suitable sealing material, and which has on its inner wall a conductive layer (7), at least part of which is transparent, that extends beyond the connection to the sealing member (6), the member being slightly recessed into the lamp vessel. The inner conductive layer can thus be connected in a simple manner to an electrical conductor, which during operation of the lamp is connected, for example, to one of the supply wires of the mains.

Abstract: A detection apparatus of a simple construction is formed from an electro-chemiluminescence cell (12) having connections for the supply and the discharge of a liquid to be examined, particularly a mobile phase coming from the separation column of a liquid chromatograph, a voltage source (11) and a detector (14) for electric current, which are connected to the electrodes (1, 2) of the cell (12). Preferably a radiation-sensitive element (13) is also provided.

Abstract: A method of making a heat-reflecting filter consisting of a tin-doped indium oxide layer on a carrier. A tin-doped indium oxide layer is provided on a carrier by spraying a heated carrier with a solution of an indium salt and a tin salt. The layer is then reduced at 350.degree.-400.degree. C. by means of a gas flow of hydrogen, nitrogen together with oxygen or air.

Abstract: The life of light-pervious, thermal radiation-reflecting filters of tin-doped indium oxide is drastically elongated when used in oxidizing or reducing medium by coating the indium oxide layer with pyrolytic or hydrolytic silicon dioxide.

Abstract: The thermal radiation which is emitted by an electric incandescent lamp is eliminated according to the invention by providing an incandescent lamp with a filter which transmits visible light and which reflects infrared radiation, which filter consists of an interference filter and a heavily doped metal oxide filter which is disposed at the side of the interference filter which is remote from the filament body.

Abstract: A light-transmitting, thermal-radiation reflecting filter which comprises a transparent support coated with indium oxide which is doped with more than 7 atomic percent of tin, calculated with respect to the number of indium atoms, has a free-electron density between 10.sup.21 and 3 times 10.sup.21 per cm.sup.3 and a plasma wavelength of less than 1.2.mu.m. The filter can be manufactured so as to have a stress-free support by heating a support, which is coated in known manner with tin-doped indium oxide, at a temperature between 300.degree.C and the softening temperature of the support material in a gas having an oxygen partial pressure of less than 10.sup..sup.-7 atmosphere.