Jerry,
I am not sure how one would use a pycnometer in situ, but the bottle
are available from Cenco or other laboratory suppliers. I would think that a
hydrometer might be made to work if the sight has enough room. They measure
specific gravity, but that differs little from density on the earth.
I am glad to see your still among the living.
Gary
Gary Karshner
St. Mary's University
San Antonio, Texas
KARSHNER@STMARYTX.EDU