I remember very little of this, I was quite young - It was on television in the mid 90's, but seemed older. My wife was telling me about the 21 grams experiment and the memory clicked into place.
Inside of a mad scientist sort of lab, with the plasma balls and everything else, a character (Who in my mind resembles Gene Wilder in Young Frankenstein) is conducting an experiment. The room is hazy, lots of hues of purple and red. He has an assistant present. They were conducting some sort of experiment to try to figure out the secrets of immortality (or possibly reanimation). I remember them "trapping" a human soul in a glass vessel to see what it weighed or what kind of volume it took up - I believe they shot someone in this vessel, and because their soul could not "escape", they did not die.