Realgar

Historical uses

Realgar was used by firework manufacturers to create the color white in fireworks prior to the availability of powdered metals such as aluminium, magnesium and titanium. It is still used in combination with potassium chlorate to make a contact explosive known as "red explosive" for some types of torpedoes and other novelty exploding fireworks branded as 'cracker balls', as well in the cores of some types of crackling stars.^{[citation needed]}

Realgar is toxic. It was sometimes used to kill weeds, insects, and rodents,^[11] even though more effective arsenic-based anti-pest agents are available such as cacodylic acid, (CH₃)₂As(O)OH, an organoarsenic compound used as herbicide.

Realgar was commonly used in leather manufacturing to remove hair from animal pelts. Because it is a known carcinogen and an arsenic poison, and because substitutes are available, it is rarely used today for this purpose.

The ancient Greeks, who called realgar σανδαράκη (sandarákē), understood that it was poisonous. From this, realgar has also historically been known in English as sandarac.

Realgar was also used by Ancient Greek apothecaries to make a medicine known as "bull's blood".^[12] The Greek physician Nicander described a death by "bull's blood", which matches the known effects of arsenic poisoning.^[12] Bull's blood is the poison that is said to have been used by Themistocles and Midas for suicide.^[12]

The Chinese name for realgar is 雄黃 (Mandarin xiónghuáng), literally 'masculine yellow', as opposed to orpiment which is 'feminine yellow'.^[13]

Realgar was, along with orpiment, traded in the Roman Empire and was used as a red paint pigment. Early occurrences of realgar as a red paint pigment are known for works of art from China, India, Central Asia, and Egypt. It was used in European fine-art painting during the Renaissance era, a use which died out by the 18th century.^[14] It was also used as medicine. Other traditional uses include manufacturing lead shot, printing, and dyeing calico cloth. It was used to poison rats in medieval Spain and in 16th century England.^[15]