a heat - resistant glass which has heat resistance sufficient for being free from viscous flowing , e . g ., at a temperature of 600 ° c . or higher , and devitrification resistance adequate for producing a panel of glass , which has , as thermal properties , an expansion coefficient equivalent or close to that of a sealing glass frit , with retaining electrical insulation properties excellent over conventional glass , and which can be used for the production of plate - shaped articles of glass such as a glass substrate , the heat - resistant glass containing , as glass components , ______________________________________ 30 - 45 % sio 2 1 - 10 % b 2 ohd 3 1 - 7 % al 2 o 3 1 - 17 % sro22 - less than 35 % bao 0 - 5 % mgoand 0 - 14 % cao______________________________________ the above % standing for % by weight , provided that the total amount of mgo + cao is over 4 % to 16 % by weight .