Doctor Duncan "Om" MacDougall asked these questions and set out to find the answers. After weighing twelve dying patients at the moment of death he had his answer: 21 grams.
On the 17th of April 1907 the 'Albany Advertiser' (WA) ran the following story:
WEIRD EXPERIMENTS BY AMERICAN DOCTORS.
Five Massachusetts physicians have for the past six years been, engaged in experiments which were intended, as their spokesman, Dr. Duncan MacDougall, of Boston, puts it, "to determine the existence or non-existence of a soul in the human body, and to determine also whether the departure of that soul from the human body is attended by any manifestation of nature that can be made evident to the material senses."
The method of finding the result, as followed by the doctors, was to place the dying patients in a bed upon one of the platforms of a pair of scales, made expressly for the purpose. These scales were so delicately constructed as to be sensitive to the weight of less than one-tenth of an ounce.
Three cases in particular Dr. Mac McDougall cited. The first, an ordinary tuberculosis patient, who was dying, was placed on the scales at the instant of death. The body lost one ounce in weight. The second test was that of another tuberculosis patient and the result was the same. The third test was that of a phlegmatic man, slow in thought and action, and it was alleged that the soul lefl slowly. The scales show no loss for one minute, and then the body loses one ounce."
At the time, many of the newspapers took an almost negative stance towards the experiments saying 'Nothing seems to be sacred to the American Scientist' and calling the experiences 'weird' and 'bizarre'.
Dr MacDougall said this about his findings into the soul:
'The soul must be some space occupying the body, either of gravitated or some other form of matter that has weight. If this theory is rejected it remains for someone to offer a solution of the mystery of the loss of weight'.
MacDougall also was convinced that the souls of a dying person gave off a light, resembling that of the 'interstellar ether'.
The results of the MacDougall soul experiments have never been reproduced, and his experimental methodology, along with the small number of human experiments carried out, did not give a great enough sample size to draw any accurate conclusions.
However he did take into accounts such things as expulsion of air from the lungs and bodily liquids and solids leaving the body (he was a doctor after all).
Regardless there are many who still go by his findings and cite them as proof of the existance of the human soul as a entity that can seperate from the mortal body.
Doctor MacDougall died October 15 1920 but will always be remembered fas the man to find the weight of the human soul; 21 grams.