My father invented this tool. I am not sure if it has an assignee or is public property now. Can you help me? Also wondered what company last used it, possibly Halliburton?
If the patent you are referencing is this one:
Well fluid stabilizer US 2739652 A Hartsell Arlis C https://www.google.com/patents/US2739652
Then it is long expired. It issued in 1956, and had a 17 year lifetime from that point. It is now in the public domain.
It was not assigned on its face, and because of its age the assignment data is not available online. You can go to the USPTO and find the physical file if you want to find out who it was later assigned to.
Hope this helps.
