US PATENT SUBCLASS 423 / 523
.~.~.~.~ Nitrogenous impurity or utilizing nitrogenous catalyst or reactant

Current as of: June, 1999
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423 /   HD   CHEMISTRY OF INORGANIC COMPOUNDS

511  DF  SULFUR OR COMPOUND THEREOF {4}
512.1  DF  .~ Oxygen containing {11}
521  DF  .~.~ Ternary compound containing hydrogen {1}
522  DF  .~.~.~ Sulfuric acid {5}
523.~.~.~.~ Nitrogenous impurity or utilizing nitrogenous catalyst or reactant {1}
524  DF  .~.~.~.~.~> Lead chamber process

DEFINITION

Classification: 423/523

(under subclass 522) Processes in which during the manufacture of the sulfuric acid a compound of nitrogen is used as a catalyst or as a reactant, or is present as an impurity which requires removal.