Abstract: This heat-insulating material comprises at least one layer of plain paper or plastic web provided on one face with a thin metal film having a thickness of 1 to 20 microns, and at least one layer of corrugated paper or pasteboard glued only along the crests of its waves to the metal coating of the first layer, the side of the corrugated web which faces the plain web layer being likewise coated with a metal film. Thus, substantially the entire area of the two metal layers are in constant mutual contact with the cavities formed by the waves of the corrugated web, which have a thickness of at least 1 to 1.5 mm. This feature and the specific arrangement of the layers are such that the metallized surfaces thereof face the direction in which the heat-flow is to be insulated, thus affording a particularly high heat-insulating efficiency.

Abstract: Incandescent lamp, in particular a halogen lamp, comprising an inner glass bulb that defines and limits an inner small space containing filament means, and at least one outer glass bulb spaced from and surrounding the inner bulb and defining at least one intermediate space. The inner glass bulb is a thick-walled quartz glass bulb that acts as a heat-storage and heat radiation reflecting means and closely surrounds the filament means, so that losses of energy by thermal convection and radiation are strongly reduced leading to an optimum luminous efficiency. For increasing the stability the wall of the inner bulb can be provided with a reinforcement of tungsten wires. Moreover the wall of the inner bulb can be made of foam glass containing inclusions of an infrared radiation absorbing substance as carbon dioxide gas and/or water vapor.