In 1907, Duncan MacDougall published a paper on the weight of the soul. Fortean Times carried an article on it in the latest issue and so does the Journal of Scientific Exploration this month.
In essence, he took volunteers who were doomed and laid them on a bed which was suspended on a scale. When they died, their body weight immediately declined by between 10 and 45 grams. The same test applied to dogs showed no weight loss on death. Then again, it was 1907 and a smaller animal's soul might not be detectable by the methods available then. It has not been repeated because Science doesn't like it.
Involuntary evacuation of bowel or bladder at death is of no relevance because that weight is still on the bed.
It looks as though the soul might have mass. Not very much, but it does suggest a cohesive existence in the physical world. If we have up to 40 grams of reality to deal with after death, then the lack of frequent manifestation is easy to explain. We end up as substantial as fog, and must draw on external energy to appear.
Scientifically, it all fits together but Science will never recognise that.