Isopropyl alcohol may work also, depending on what kind of glue it is. And I don't think it will hurt the coin.
Like @Paddy54 said, the color may be different under the glue. Here is a cent that I soaked in acetone to remove an adhesive of some kind. The photos are of the coin and the adhesive after it was remove.
I'm not sure. I was amazed that this material floated right off without damage to the foreign material or to the surface of the coin. I am not sure what the material is. You can see that it was transparent.
Do you recall as a kid the brown / dark amber glue that came with a red nipple on top to glue things together ? It was before Elmers white wood/paper glue...you find it on old collections all the time. I bet that's what was used.
Acetone works very well on glue and such on metals. I've never experienced any type of conflict with any agents.
We used it when we were kids for Jock Itch, and cuts. My wacky mother made us eat it when we had the runs and she also put it in stews.
I doubt it is mucilage glue as that would come off easily. Le Page Mucilage glue was in every household for years and you can still buy it, but there are so many better adhesives now that it has become a specialty. For those that need more information than necessary, this is from Wikipedia: Mucilage is edible. It is used in medicine as it relieves irritation of mucous membranes by forming a protective film. It is known to act as a soluble, or viscous, dietary fiber that thickens the fecal mass, an example being the consumption of fiber supplements containing Psyllium seed husks. So @charley is correct about mom's using it to help junior "heal." LOL
