titles
The Slave Dancer
Witch of Blackbird Pond (may be a little too early)
Anything by Nathaniel Hawthorne (writes in the 1800s about the 1700s)
Charles Dickens also wrote in the 1800s about the 1700s
Look at your own shelves, at home. You probably have adult fiction that illustrates the language.
The documents surrounding American independence would be good examples. This is hard reading, but it was a long time ago! John Locke (maybe just a paragraph) would illustrate it. Ben Franklin's Poor Richard Almanac would be interesting, fun, and approachable.
Look for the America Firsthand series. It's for high school and college students, but I use selected passages as read-alouds in sixth grade. These are eyewitness accounts of big events in American history. I can't use a lot, as the language really is a barrier for kids my kids' age, but it authentically illustrates the language of the time.