Granted Patent
Utility
US 4,971,918 · App. 07/198,765
Reducible indicator compositions containing pyrogallol derivatives
Inventors:
Lee Bouse, Michael C. Phillips
Patented Case
View Patent ↗
Granted: Nov 20, 1990
Filed: May 25, 1988
Inventors
Lee Bouse
Michael C. Phillips
Assignee (at issue)
Boehringer Mannheim GmbH
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.