google.com/patents/US422233 … CB0Q6AEwAA
The above link is to the patent mentioned in the recent IAA Journal #499. Great job and interesting reading as always!
Casimir Krystyniak worked with my father at the GE R&D center in Niskayuna, NY. Mr. Krystyniak worked on research in high temp ceramics ( re-entry heat shields for the space program etc.) and many of them are by design magnetic. My father held many patents with GE for methods and procedures for producing man made diamonds. They were the first to produce diamonds in the lab and the first gem quality stones. The Smithsonian has a display of his first diamond production at GE. Mr Kyrstyniak worked occasionally with the high pressure lab (GE’s “diamond mine”) to try to “tag” man made gem stones for ID purposes. Introducing ferrite to the diamond /carbon material caused some problems and was abandoned.
google.com/patents/US629320 … CCsQ6AEwAg
This link is another patent related to tagging cartridges and projectiles.