Glass and use of a glass for glass-metal compounds

The glass comprises silica (75-80 wt.%), boron trioxide (4.5-6 wt.%), alumina (2-4.5 wt.%), sodium oxide (5.5-7 wt.%), potassium oxide (0-2 wt.%), calcium oxide (2.5-8 wt.%), magnesium oxide (0-2 wt.%), barium oxide (0-4 wt.%), titanium oxide (0-5 wt.%), cesium oxide (0-2 wt.%), ferric oxide (0-0.1 wt.%), fluorine (0-2 wt.%). The ratio of aluminum oxide and boron trioxide is less than 5 mol% to the amount of magnesium oxide, calcium oxide and barium oxide, for a glass tube in a tube collector with a glass-metal-compound. The glass comprises silica (75-80 wt.%), boron trioxide (4.5-6 wt.%), alumina (2-4.5 wt.%), sodium oxide (5.5-7 wt.%), potassium oxide (0-2 wt.%), calcium oxide (2.5-8 wt.%), magnesium oxide (0-2 wt.%), barium oxide (0-4 wt.%), titanium oxide (0-5 wt.%), cesium oxide (0-2 wt.%), ferric oxide (0-0.1 wt.%), fluorine (0-2 wt.%). The ratio of aluminum oxide and boron trioxide is less than 5 mol% to the amount of magnesium oxide, calcium oxide and barium oxide, for a glass tube in a tube collector with a glass-metal-compound. The amount of calcium oxide, magnesium oxide, barium oxide, strontium oxide and zinc oxide is greater than 3 wt.%. The glass consists of 100-150 ppm of ferric oxide. The glass consists of named components up to pollution. The metal/metal alloy of the glass-metal compound is a covar alloy. Die Erfindung betrifft die Verwendung eines Glases, enthaltend folgende Bestandteile: SiO 2 72 - 80Gew.-%, B 2 O 3 4 - < 6 Gew.-%, Al 2 O 3 2 - 5 Gew.-%, Na 2 O 4 - 7 Gew.%, K 2 O 0 - 3 Gew.-%, CaO 2,5 - 8 Gew.%, MgO 0 - 2 Gew.-%, BaO 0 - 4 Gew.-%, TiO 2 0-5 Gew.-%, CeO 2 0 - 2 Gew.-%, Fe 2 O 3 0 - 0,1 Gew.-%, F 0 - 2 Gew.-%, wobei im Glas das Verhältnis der Summe aus Al 2 O 3 und B 2 O 3 (in mol-%) zu der Summe aus MgO, CaO und BaO (in mol-%) < 5 beträgt, für ein Glasrohr in einem Röhrenkollektor mit einer Glas-Metall-Verbindung. Die Erfindung betrifft auch das Glas selbst.