# White arsenic

*Arsenic; “inheritance powder”*

**Known today as.** Arsenic trioxide.

Kind: Mineral  
Poisoning: Mercury, arsenic, lead, and antimony (https://thethinkingpress.org/materia-medica/poisons/heavy-metal)  
Deadly: yes

> **Deadly.** 

## What was it used for?

Caustic for cancers of the skin; in small doses against agues; and the favorite poison of history.

## What does modern science say?

Deadly; yet arsenic trioxide is today an approved and effective drug for one form of leukemia. Arsenic kills by binding the enzymes of the cell’s energy; a hundred milligrams is a fatal dose. Yet in 2000 arsenic trioxide was approved in the United States for acute promyelocytic leukaemia, in which, with retinoic acid, it cures most patients, and it is on the World Health Organization’s list of essential medicines. Paul Ehrlich’s arsphenamine, Salvarsan, the first drug against syphilis, was an arsenical too.

## Pharmacognosy and toxicology

- **arsenic trioxide**: 

**Mechanism.** Trivalent arsenic binds the thiol groups of enzymes, above all those of cellular respiration.

**Dose.** About 100–200 mg; 2 mg per kilogram.

**Standing.** Arsenic trioxide is on the WHO list of essential medicines for acute promyelocytic leukaemia.

## What lore surrounds it?

Tasteless, odourless, and cheap, it was the poison of the Borgias in legend and of the Victorian poisoners in fact, until James Marsh’s test of 1836 could find it in a body; after that the poisoners turned elsewhere. Madame Bovary dies of it. Green wallpapers coloured with arsenic were blamed for sickrooms that would not mend, and the Scheele’s green of Napoleon’s rooms on St Helena has been offered as his killer.

## What did the older authorities say?

**The Affair of the Poisons.** In the Paris of the 1670s, fortune-tellers such as La Voisin sold *poudre de succession*, “inheritance powder,” to heirs impatient for their legacy.

**Thomas Fowler.** In 1786 the Stafford physician published his solution of arsenic in potash, flavoured with lavender, for agues; Fowler’s solution was prescribed for a century and a half for everything from asthma to leukaemia, and Darwin took it.

**The Styrian arsenic-eaters.** Peasants of the Austrian Alps, reported in 1851, ate white arsenic by the grain for strength and a clear complexion, and some took doses that would kill the unaccustomed.

## Sources

- Somerset, A. (2003). *The Affair of the Poisons: Murder, Infanticide, and Satanism at the Court of Louis XIV*.
- Fowler, T. (1786). *Medical Reports of the Effects of Arsenic in the Cure of Agues*.
- Emsley, J. (2005). *The Elements of Murder*. Oxford University Press.
- Emsley, J. (2005). *The Elements of Murder*.

---

*White arsenic.* In *Materia Medica*, edited by B. C. P. Statema. Version 1, revised 2026-10-01. The Thinking Press. https://thethinkingpress.org/materia-medica/white-arsenic

Historical description, not medical advice.