Was Napoleon killed by his wallpaper?

In a Slate review of Elements of Murder: A History of Poison by John Emsley, Daniel Kevles writes:

Twenty years after he died in exile on St. Helena, Napoleon's body was exhumed for reburial in Paris. The exceptional preservation of his corpse, which could be chemically tested along with years' worth of hair cuttings, revealed that his body contained high levels of arsenic. The symptoms of Napoleon's final illness were also consistent with arsenic poisoning. Armchair analysts theorized that he had been done in by the British or by a jealous husband. But Emsley argues that Napoleon was killed by his wallpaper—or more precisely, drawing on the work of an Italian scientist named Bartolomeo Gosio, by the green, arsenic-rich pigment in the wallpaper's star pattern.

At the end of the 19^th century, Gosio was prompted to investigate why so many Italian children were inexplicably sickening and dying. Physicians suspected arsenic poisoning. Gosio demonstrated that a microorganism that grew on the flour-paste backing of the wallpaper could turn the arsenic in it into a gas that was powerful enough to make people ill and even kill them. If Napoleon chose the colors of his wallpaper to commemorate his imperial colors, Emsley writes, "[H]e did himself no favours … though they reminded him of his glorious past." Napoleon seems to have been a victim, like so many others, of a surreptitious killer. But he may have been poisoned by his own vanity rather than by a self-protective lover, a grasping wife, or a woman like the Lucrezia Borgia of historical repute.

Other uses of arsenic

Arsenic not only persists in the remains of anyone who has ingested or inhaled it, but it also acts as a preservative. It has been employed in embalming solutions and in dry preservatives used by taxidermists such as Becoeur soap , which was "made of arsenic powder, camphor, tartaric acid and lime" or "the arsenic  soap made of white soap flakes, arsenic salts, potash, camphor, alcohol and water, borax powder . . . " etc. (Tissier & Migne). The "miraculous preservation" of corpses can sometimes be attributed to the presence of arsenic in the soil in which they have been buried .