[4] Calomel was taken internally and used as a laxative,[4] for example to treat George III in 1801, and disinfectant, as well as in the treatment of syphilis, until the early 20th century.

it was also used as a horticultural fungicide, most notably as a root dip to help prevent the occurrence of clubroot amongst crops of the family Brassicaceae.

[7] Mercury became a popular remedy for a variety of physical and mental ailments during the age of "heroic medicine".

It was prescribed by doctors in America throughout the 18th century, and during the revolution, to make patients regurgitate and release their body from "impurities".

Benjamin Rush was a well-known advocate of mercury in medicine and used calomel to treat sufferers of yellow fever during its outbreak in Philadelphia in 1793.

Ammonia causes Hg2Cl2 to disproportionate: Mercurous chloride is employed extensively in electrochemistry, taking advantage of the ease of its oxidation and reduction reactions.

Calomel was also a common ingredient in teething powders in Britain up until 1954, causing widespread mercury poisoning in the form of pink disease, which at the time had a mortality rate of 1 in 10.

It has also found uses in cosmetics as soaps and skin lightening creams, but these preparations are now illegal to manufacture or import in many countries including the US, Canada, Japan and the European Union.