Marsh test

The Marsh test is a highly sensitive method in the detection of arsenic, especially useful in the field of forensic toxicology when arsenic was used as a poison. It was developed by the chemist James Marsh and first published in 1836. The method continued to be used, with improvements, in forensic toxicology until the 1970s. Arsenic, in the form of white arsenic trioxide , was a highly favored poison, being odourless, easily incorporated into food and drink, and before the advent of the Marsh test, untraceable in the body. In France, it came to be known as ("inheritance powder"). For the untrained, arsenic poisoning will have symptoms similar to cholera. Precursor methods The first breakthrough in the detection of arsenic poisoning was in 1775 when Carl Wilhelm Scheele discovered a way to change arsenic trioxide to garlic-smelling arsine gas (AsH3), by treating it with nitric acid (HNO3) and combining it with zinc.