In 1907, A physician from Haverhill, Massachusetts named Duncan MacDougall, Published a scientific study detailing his experiments to determine if the human soul possessed any material weight to it.
He set out to scientifically determine if the ethernal soul had weight.
He identified six patients in nursing homes whose deaths were imminent. Four suffering from tuberculosis, one of diabetes, and one from unspecified causes. MacDougall specifically chose people who were suffering from conditions that caused physical exhaustion, as he needed the patients to remain still when they died to measure them accurately.
On a specially designed scale bed, he recorded not only each patient’s exact time of death, but also their weight the total time on the bed, as well as any changes in weight that occurred around the moment of expiration. He even factored losses of bodily fluids like sweat and urine, and gases like oxygen and nitrogen, into his calculations. His results were mixed, but he concluded that there was a very slight loss of weight of 21 grams on average.
In reference to one patient, MacDougall told the Times, “The instant life ceased the opposite scale pan fell with a suddenness that was astonishing, as if something had been suddenly lifted from the body.”
His papers were met with harsh ridicule and criticism, Psychologist Bruce Hood wrote that "because the weight loss was not reliable or replicate-able, and his findings were unscientific"
Despite receiving criticism for his ideas, MacDougall also had his supporters. While the scientific integrity of his study is doubted, some point to the unexplored nature of his research in the first place, and that there’s so much, experts still don’t understand.
To back up his findings further, he conducted the same experiment on 15 dying dogs. This was because he believed animals do not posses souls. Unfortunately for the dogs, there was no change in weight after the death of the animals. MacDougall said he wished to use dogs that were sick or dying for his experiment, sadly though was unable to find any. It is therefore presumed he poisoned healthy dogs.
The 1911 The New York Times reported that MacDougall was hoping to run experiments to take photos of souls, but he appears to not have continued any further research into the area and died in 1920. His experiments have never been repeated.