Granted Patent
Utility
US 4,781,909 · App. 06/865,216
Process for removing boron from sulfuric acid
Inventors:
Francis E. Evans, Joel P. Guptill
Patented Case
View Patent ↗
Granted: Nov 1, 1988
Filed: May 19, 1986
Inventors
Francis E. Evans
Joel P. Guptill
Assignee (at issue)
AlliedSignal, Inc.
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.