Overview
On 4 July 1850 the president attended a ceremony at the unfinished Washington Monument. It was hot. Afterwards he ate cherries and drank iced milk, or possibly iced water — the accounts vary in the way accounts of ordinary afternoons do when something happens later. That evening he developed severe stomach cramps and diarrhoea. He died on 9 July, sixteen months into his term.
His doctors recorded the cause as cholera morbus, a nineteenth-century catch-all covering acute gastroenteritis of almost any origin. Washington's water supply was contaminated, the summer was hot, and the diagnosis was unremarkable to anyone at the time.
Why Anyone Wondered
The political timing is the whole of the case, and it is genuinely striking.
Taylor was a Louisiana slaveholder and a career soldier who had never held office before the presidency, and southern politicians had assumed he would be theirs. He was not. He wanted California admitted as a free state and New Mexico organised without waiting for the territorial compromise being assembled in the Senate, and he had told visiting southern leaders that he would take the field personally against secession and hang anyone who took up arms against the Union.
That position was the principal obstacle to the package of measures being negotiated. Taylor died in July. Millard Fillmore, his vice president and a supporter of the compromise, signed its component bills in September. A crisis that had looked like it might break the Union in 1850 was postponed for a decade.
A president whose death removes the last obstacle to a settlement, weeks before that settlement passes, is the kind of sequence that invites a second look regardless of the medicine.
Clara Rising
The second look came in 1991, and it came from a former University of Florida humanities professor named Clara Rising, who was researching Taylor and became persuaded that arsenic was the likelier explanation. Arsenic poisoning produces gastrointestinal symptoms that a nineteenth-century physician would have had no way to distinguish from cholera morbus.
Rising made the argument well enough to persuade Taylor's closest living relative and the coroner of Jefferson County, Kentucky. On 17 June 1991 the president's remains were removed from the mausoleum at what is now Zachary Taylor National Cemetery in Louisville and taken to the office of the state chief medical examiner.
The Tests
Samples of hair, fingernail and other tissue were subjected to neutron activation analysis at Oak Ridge National Laboratory — a technique capable of detecting arsenic at trace levels, and one that works on remains far older than these.
Dr George Nichols, Kentucky's chief medical examiner, announced the results at a press conference: the levels found were consistent with ordinary nineteenth-century background exposure and hundreds of times below what a fatal dose would leave. The tests also screened for lead and mercury, and those were negative too. Taylor's remains were returned to the mausoleum the same day.
Rising accepted the finding on arsenic while maintaining that other poisons had not been excluded, which is technically correct and is where the matter has rested.
What Survives the Result
The exhumation is often cited as the end of the theory, and for the arsenic version it is. What it did not resolve is the wider question, because the wider question was never really forensic.
Several of the alternatives leave no signature that neutron activation analysis would find. Some poisons available in 1850 do not persist in tissue at all. And the mundane explanation carries its own uncomfortable possibility: if the president died of contaminated food or water in a city whose sanitation was notorious, the distinction between an accident and an opportunity is thinner than it looks, and would have left exactly the same evidence.
What the case retains is its shape. A president in the way of a settlement dies suddenly; the settlement passes; the man who signed it was the man who inherited the office. The 1991 tests eliminated the specific mechanism most often alleged. They could not do anything about the sequence, which is what made anyone curious in the first place.