Granted Patent
Utility
US 5,403,571 · App. 07/700,149
Purification of elemental sulphur
Inventors:
Michael E. Chalkley, Michael J. Collins, Manher M. Makwana, Ian M. Masters
Patented Case
View Patent ↗
Granted: Apr 4, 1995
Filed: Apr 4, 1991
Inventors
Michael E. Chalkley
Michael J. Collins
Manher M. Makwana
Ian M. Masters
Assignee (at issue)
Sherritt Gordon Limited
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.