In 1955, the diaries of Napoleon's valet, Louis Marchand, were published. His description of Napoleon in the months before his death led Sten Forshufvud in a 1961 paper in Nature to put forward other causes for his death, including deliberate arsenic poisoning. Arsenic was used as a poison during the era because it was undetectable when administered over a long period. Forshufvud, in a 1978 book with Ben Weider, noted that Napoleon's body was found to be remarkably well preserved when moved in 1840. Arsenic is a strong preservative, and therefore this supported the poisoning hypothesis. Forshufvud and Weider observed that Napoleon had attempted to quench abnormal thirst by drinking large amounts of orgeat syrup that contained cyanide compounds in the almonds used for flavouring.
 What was the possible cause for Napoleon's death suggested in a 1961 Nature paper?
arsenic poisoning