I'm about 2/3rds of my way through the book, but have been reading a lot at night before bed when I'm sort of tired, and some how I feel like I missed (or forgot) something.  I am at the part right where John the Dig has died, leaving Adeline and the boy....  what happened to Emmeline?  When did she become all unattached and mute?  Was this after the experiment where they were separated?  Thanks!

You have to keep reading, it reveals at the end.

Yes, read more.  I remember there was a point about 2/3s of the way thru where I said "what? what? what?" and then it all gets explained later.

Yep, as Mimi said, just keep reading.  I also wondered "did I skip some pages or something?!" when I read it, but it all gets explained.