Is the crusty material on an ancient Roman coin “old dirt” or “oxidized metal”?

In a lesson crossing the humanities and physics curricula, Providence Hall humanities teacher Bruce Rottman and science teacher Laura Schultheis recently team-taught freshman students a lesson about ancient Roman coins and using the principles of electrolysis to clean the coins.

Rottman began the class session with a lesson on the fall of Rome in 476 A.D., the resulting loss of millions of coins under layers of dirt, and the eventual recovery of those coins by modern-day treasure hunters.

Schultheis followed the history lesson with a review of the principles of oxidation and the attraction of positive and negative charges in an ionic electrolytic cell. She set up a lab for the students, using a salt water solution, an iron nail, an ancient copper coin and a low-voltage battery. When students attached the coin to the cathode (negative electrode) and the nail to the anode (positive electrode) and then immersed both in the salt-water solution, the solution bubbled and fizzed around the coin as the layers of corroded material fell away. After about a half-hour in the solution and some vigorous rubbing with olive oil, the coins were visibly “cleaner” or less corroded.

”This is a great example of our integrated approach to curriculum, with collaboration by our humanities and science teachers,” said Tim Loomer, academic dean. “Of course, the educational value of an activity of this nature is incalculable, but perhaps of most worth is students watching their humanities and science instructors working together on an academic endeavor. This is what the future work force holds for them.”

After about a half-hour in the solution and some vigorous rubbing with olive oil, the coins were visibly “cleaner.” (Providence Hall photo)

Students appreciated both the teacher collaboration and the lab activity.

“I really appreciated you taking the time to engage with us outside of our physics class,” freshman Gabriel Clark told Schultheis. “The process was very interesting, and I was surprised with the results I gathered.”

Freshman Maddy Niessen added: “I thought it was really fun to do an experiment and to actually use coins from thousands of years ago. It was really awesome that when we finished cleaning the coins, we could see the faces on them.”

Schultheis deems the collaborative teaching experiment a great success.

“We will do this again next year, for sure,” she said.

— Elaine Rottman is the director of advancement at Providence Hall.