In 1832 the English chemist James Marsh came up with a simple test for arsenic that essentially put an end to its rather common use as a poison. With the advent of the Marsh Test people could test their food and drink to determine if they were being poisoned. The food sample is mixed with zinc and sulphuric acid. Any arsenic present causes the production of arsine gas and hydrogen. When the gas impinges on a cold surface, a mirror-like deposit of arsenic forms.