I usually soak it in hot/warm water for about 30 minutes and then just use a washcloth or something to try and get it out a little at a time and if that doesn't work I soak it in hot soapy water and try it that way. I think the soapy water would do better for you. It usually works for me.
I hope this helps in some way.
I think this is the correct answer! Hope it helps :)
I believe that would be the 18th Century