Copper Coins in Stock Pot?

I was watching a restaurant video posted in the "RESTAURANT WEBSITES, ACCORDING TO THE OATMEAL." thread and was baffled by something.

tcdup wrote:I was looking at restaurants in Krakow, and came across this nifty website. Love the little movie that shows the restaurant from daybreak to end of service that plays when you first go to the site:
http://www.podaniolami.pl/en

At approx. 1:50 in the opening video, a woman removes what looks like a bunch of copper coins attached by wires to a frame from what looks to be a stock pot. Any ideas as to what is going on there?

What a great video! Watch the whole thing. Those fat pierogi! The flaming ham! What a thing to watch when searching for inspiration for tonight's dinner. Thanks very much for posting it.

Oh by the way, I have no idea what those copper coins are for!

Found it!

from their complete menu pdf:

Soup
Traditional Old-Polish broth cooked with gold coins (“such a broth the blood
purges, improving one’s health” - as described in Pan Tadeusz, the masterpiece
by Adam Mickiewicz), cooked with the use of several kinds of meat
and vegetables, served in a cup with a French pastry finger.

Festal broth, according to Old-Polish tradition cooked with gold coins
to indulge whim and for health, served with chicken leg and selection
of vegetables, by a recipe found in Stanisław Czerniecki of Cracow
Compendium Ferculorum - first Polish cook book from 1682.

Hi,

A friend was a historical interpreter who made period food at historic homes. Once she caused a mass illness by preparing a meal in an unlined copper pot. I knew nothing of this story until after she died. She must have been very embarrassed.

Regards,
Cathy2

I've heard of using copper coins on steam pots so you can tell when it's running low by the rattling... But I've been told not to do it with newer pennies which are mostly zinc.