US PATENT SUBCLASS 501 / 78
.~.~.~.~.~ And rare earth (i.e., elements with atomic number 39 or 57-71)

Current as of: June, 1999
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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}
77  DF  .~.~.~.~ And boron {2}
78.~.~.~.~.~ And rare earth (i.e., elements with atomic number 39 or 57-71)

DEFINITION

Classification: 501/78

And rare earth (i.e., elements with atomic number 39 or 57-71):

(under subclass 77) Compositions additionally containing a rare earth element or a compound of any rare earth element.

(1) Note. For the purpose of this classification, rare earth elements are those having atomic numbers 39 or 57-71.