| 501 / | HD | COMPOSITIONS: CERAMIC |
| 1 | DF | CERAMIC COMPOSITIONS {15} |
| 11 | DF | .~ Glass compositions, compositions containing glass other than those wherein glass is a bonding agent, or glass batch forming compositions {11} |
| 53 | DF | .~.~ Silica containing {3} |
| 73 | DF | .~.~.~ Less than 40 percent by weight silica {2} |
| 74 | DF | .~.~.~.~ And lead {1} |
| 75 | DF | .~.~.~.~.~ And boron {1} |
| 76 | | .~.~.~.~.~.~ And zinc |