When I was a kid in Minnesota, in the 30s and 40s, the daily milk (unhomogenized in those days) delivery came in a quart glass bottle (no surprise there!), but the bottle had a constricted neck, with a wider bulb above it; I guess you might call it a cream reservoir.
    The cream from the milk rose, of course, and we had what I'd call a runcible spoon, sort of a little dipper or ladle shape, just the right diameter to block the restricted neck, so that we could pour off the cream above it for whatever use we had for cream. When the cream in the bulb was poured off, it left what I suppose was maybe an ounce or ounce and a half of cream with the remainder of the quart of milk, so that it wasn't really skim milk as we'd buy it today. I don't know what the resultant butterfat percentage was.

Dave Oesterreich