PAST CRIMESchanged her story, saying the poisoning of Dazley had been an accident. Two
chemists gave evidence that they had sold poison to Sarah, and Waldock
testified that Sarah had threatened Dazley’s life.
She was found guilty and sentenced to death at Bedford, with a crowd of
12,000 coming to watch her hang.^8
It was advances in the detection of arsenic that brought about Sarah’s
downfall. Arsenic was the poison of choice for many murderers of the time–
tasteless, easy to put into food, and its symptoms were similar to those of food
poisoning, cholera and dysentry. There would be vomiting, stomach pains,
diarrhoea and cramps. It is naturally present in the human body in microscopic
amounts and it was commonly available to use as rat poison. Death can occur
either quickly with a large dose, or more slowly if small doses are administered
over a longer period of time. Inhalation of the vapour or absorption through the
skin are eventually as fatal as direct ingestion. James Marsh noted that arsenic
remains in the body even after death and can be detected in the hair and bones,
and he devised a chemical proof for the presence of arsenic in 1836.
The Marsh Test involved adding fluid obtained from the body to sulphuric
acid onto a piece of zinc. With no arsenic present, hydrogen will be produced,
but in the presence of arsenic, arsine gas will be produced. If this gas is lit and
a piece of glass is held over the flame, arsenic will be deposited on the glass.
This test can identify amounts as small as onefiftieth of a milligram.
In 1851 the Arsenic Act was passed by Parliament. Under its terms, only
those known to the pharmacist could buy the poison, and their names were
recorded in a Poisons Book. Arsenic could no longer be sold as an innocent
seeming white powder–it now had to be mixed with indigo or soot, to avoid
accidental use in place of salt or sugar, and to make life for the wouldbe
murderer much harder.^7
A pioneer of scientific methods of investigation was Dr Alexandre
Lacassagne, a university head of a department of legal medicine, who was
called upon by the city prosecutor of Lyon to examine a body that had been
exhumed. The remains had been buried for four months, after having been
foundin a sack in the River Rhône. An autopsy had failed to identify the
deceased, but it was believed that it might be the body of ToussaintAugustin
Gouffé, a Parisian widower. Gouffé had gone missing towards the end of
July, and his brotherinlaw had reported this to the police, but no trace had
been found.
Then, 300 miles away and three weeks later, the body turned up in the
River Rhône. A broken trunk with a shipping label from Paris was found in
nearby woods shortly afterwards.