12 HIGH TEMPERATURE RESISTING ARTICLES-NAMELY, BLOCKS, TUBES, AND OTHER SHAPES, AND POWDER USED FOR HEAT INSULATION PURPOSES AND TO EMBED ARTICLES FOR FIRING IN KILNS OR FURNACES, AND CORROSION RESISTANT ARTICLES-NAMELY, BLOCKS, TUBES, AND OTHER SHAPES, MADE OF FIRED VITREOUS MATERIALS AND USED FOR CONSTRUCTING VESSELS OR PIPES OR LINERS FOR VESSELS OR PIPES FOR CONTAINING OR TRANSPORTING CORROSIVE SUBSTANCES-NAMELY,CORROSIVE CHEMICAL SOLIDS CORROSIVE CHEMICAL BATHS, AND CORROSIVE CHEMICAL VAPORS, THE CORROSIVE CHEMICALS BEING ACID, BASIC, OR ACID AND BASIC MIXTURES