Doctor MacDougall postulated the soul was material and therefore had mass and that a measurable drop in the weight of the deceased would be noted at the moment that their spiritual essence parted ways with the physical remains.
Dr. MacDougall was seeking to determine if the psychological functions of the mind continue to exist as a separate individuality or personality after the death of brain and physical body. To determine this Dr. MacDougall fabricated a special bed in his office which was constructed of a lightweight framework built upon a very delicately balanced platform of beam scales which were sensitive to two-tenths of an ounce.
To begin his experiment Dr. MacDougall recruited six volunteers who were in the final stages of terminal illnesses. Four of these patients were dying from tuberculosis, one from diabetes, and one from unspecified causes. Dr. MacDougall then started a process in which he observed them before, during, and after the process of death during which time he measured any corresponding changes in weight.
In a portion of Doctor MacDougall’s notes we find that he attempted to eliminate as many physiological explanations for the observed results as he could conceive:
“The patient’s comfort was looked after in every way, although he was practically moribund when placed upon the bed. He lost weight slowly at the rate of one ounce per hour due to evaporation of moisture in respiration and evaporation of sweat. During all three hours and forty minutes I kept the beam end slightly above balance near the upper limiting bar in order to make the test more decisive if it should come.
At the end of three hours and forty minutes he expired and suddenly, coincident with death, the beam end dropped with an audible stroke hitting against the lower limiting bar and remaining there with no rebound. The loss was ascertained to be three-fourths of an ounce.”
It was this experiment which was the most famous. MacDougall’s first test subject whom MacDougall claimed decreased in weight by three-fourths of an ounce, which is 21.3 grams, is the famed “weight of the soul” which eventually became the title of a 2003 movie. MacDougall repeated the experiment with his five other volunteers who all lost between ½ an ounce and ¾ of an ounce.
Dr. MacDougall repeated his experiment with fifteen dogs and observed that the results of the experiment were uniformly negative which indicated no loss of weight at death. This result seemingly corroborated Dr. MacDougall’s hypothesis that the loss in weight recorded as humans expired was due to the soul’s departure from the body, however since there was no loss in the animals weight at death this also confirmed his religious convictions that animals do not have souls.
In March of 1907 the accounts of Dr. MacDougall’s experiments were published in the New York Times and in the medical journal American Medicine. Fellow Massachusetts doctor Augustus P. Clarke took MacDougall to task for failing to take into account the sudden rise in body temperature at death when the blood stops being air-cooled via its circulation through the lungs. Clarke posited that the sweating and moisture evaporation caused by this rise in body temperature would account both for the drop in the men’s weight and the dogs’ failure to register any decline in weight as dogs do not have sweat glands, they pant to cool themselves.
Although Dr. MacDougall passed away in 1920 his ideas live on. There are still many persons today who believe, at the moment of death, the soul leaves the body and the mass of the remains decrease by the famed 21 grams. Unfortunately, the reality of Dr. MacDougall’s experiments did not demonstrate any credible evidence about post-mortem weight loss, much less the quantifiable existence of the human soul. When researched we find that Dr. MacDougall’s results were far from consistent and his methods were sloppy at best. Dr. MacDougall’s results were flawed because of the methodology he used to harvest the data, the sample size of the experimental group was far too small, and the ability to measure changes in weight were less than precise. For these reasons no credence should be given to the idea that his experiments proved anything, let alone that they measured the weight of the soul as exactly 21 grams.
(Info found on Wikipedia)