Mysterious Money inside an 18th century Metastasio

I usually blog these little stories after I've had my fun digging into their ancient secrets. But this time I'm doing it at the beginning, because I feel there will be someone out there who knows a lot more about 18th century Italy than I do. So here goes.

Item. A stained but sound vellum-bound copy of Tomo I of the Opera del Signor Ab Pietro Metastasio, put out by the Press Antonio Zatta, Venice in 1781. This volume contains his ARTASERSE, produced at the Teatro Delle Dame in Rome at the Carnevale of 1730 and ADRIANO IN SIRIO, and a large part of the volume is taken up by an enormous list of the gentlemen subscribers who had enabled the printing.

Nicely illustrated, and the ARTASERSE, of course, is a major piece of theatre. But what attracted my attention were a pair of 'bookmarks', slipped inside the volume. Here they are.

Well, I had to look. Just in case it was all obvious. It appears that they are 'money', used in 'Palmanova in a state of siege' in 1848. Yes, indeed! There's one on eBay selling for -- good heavens 250 pounds!
Well, I know less than nothing about Palmanova, except that it was part of Austria at one stage and then part of Italy, and .. ah, here is a website called thecurrencycollector.com. Splendid site, everything explained perfectly.
The 1848 siege lasted only from April to the end of June before the Italians had to give into Radetzky's armies. Not time to issue a huge amount of 'rebel' currency.
'The second siege of Palmanova has left us with several numismatic rarities' he relates. Oooooh! And he goes on to describe the notes above in precise detail. Three colours - red, white, and green, signed by four dignitaries of the short-lived 'siege city' ...

I wonder why these notes have been slipped into my grandmother's copy of Metastasio. Is the book a family item, or is it just something she bought. I suppose I'll never know.
But now at least I know about Palmanova.