These 30mL PYREX® high form crucibles have 30mm diameter medium porosity (10 to 15µm) fritted discs. They are particularly adapted to analytical work where precipitates are dried to constant weight at 110°C. They are also suitable for higher temperatures, in which case it is advisable to heat in an electric furnace. Crucibles should not be subject to sudden temperature changes. In order to avoid strain, they should not be removed from the furnace until the temperature has dropped to 250°C. PYREX® filter tubes (Item Nos. COR-9480-20 & -25) are often used on the bottom of these crucibles to collect the filtrate. 12/Case. Corning #: 32940-30M. Capitol #: COR-32940-30M.