DENSITOMETER

You may know or have heard that it is nearly impossible to dive completely underway in either the Great Salt Lake in Utah or the Dead Sea in Palestine because the water is so salty that it is much denser than ordinary sea water. You float too high in those two lakes to sink. So let's make use of that principle [of Archimedes]. In a car battery densitometer, the liquid is drawn up into the large syringe so that the float floats freely. The float is weighted with lead shot, and the skinny neck topside is calibrated. (For other uses, the floats can be bought separately, and, of course, the calibrations are adjusted for the purpose.)