Granted Patent
Utility
US 5,118,344 · App. 07/424,159
Recovery of silver
Inventor:
Philip John Watkiss
Patented Case
View Patent ↗
Granted: Jun 2, 1992
Filed: Oct 19, 1989
Inventor
Philip John Watkiss
Assignee (at issue)
E.I. DU PONT DE NEMOURS AND COMPANY
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.