I'll have to try it and report. I'll also heat up some smaller rocks and see if it really boils water like I've read.

Also, rereading that section of the book, he says they should be "red hot". I don't think I've ever seen a red-hot rock.

Half the people around here say all the rocks here are glacial. The other half say it's old river rock. I guess I'd better find some dry bricks...

Sue