We ran out of the first batch of butter we made, so I bought more cream and made some more. This time, however, I did it right.
I shook the jar until it all solidified, just like before, only this time I shook a little more. It only took a few more firm shakes, enough to move a semi-solid mass of cream, when suddenly it filled with liquid again--buttermilk!
The butter was now yellow (our last batch was white) and had the consistency of butter. It even harden in the refrigerator, which the last batch did not. And ds#3, who didn't care for the last batch, loves this one (he has discerning taste.)
I replaced the stick butter in my decorative butter dish instead of keeping it in the jar. I estimate that I got a pound out of the quart of cream, plus about a 12 oz of buttermilk.