‘Arsenic’ is sometimes called ‘the king of poisons’. But already in the sixteenth-century ‘arsenic’ was available in several different forms, each more or less suited to the job in hand. This article looks at the main alternatives, and the problems that a tyro poisoner might have with sourcing and administering their preferred choice. [The featured image is by Earth’s buddy, on Wikipedia.]

1. The red, yellow and white, or: What we talk about when we talk about Arsenic1

Properly speaking, according to modern chemistry, ‘arsenic’ (symbol As) is one of the hundred-plus chemical elements from which all material things are compounded.2 (Of course, nobody in Tudor times had much inkling of this.) In the natural world, however, arsenic is very rarely found in its pure, elemental form. In nature arsenic is almost always found in combination with other elements, especially with sulphur (symbol S).

Thus there are two main naturally-occurring ores of arsenic, namely, ‘orpiment’ and ‘realgar’. Both have been known since classical times. Whereas pure elemental arsenic is a grey, metallic material, orpiment and realgar are quite different – as is almost always the case with chemical compounds. 3

Realgar crystals, Royal Reward Mine, King County, Washington, US Rob Lavinsky, iRocks.com – CC-BY-SA-3.0. Wikipedia.

Orpiment (As2S3) is found as yellow crystals or powder. In some ways orpiment is the original ‘arsenic’, because its ancient Greek name was ‘arsenikon’ (or ‘arrenikon’). To the Romans it was known as ‘auripigmentum’, i.e. ‘gold pigment’, for fairly obvious reasons. In medieval vernacular this was corrupted to ‘orpiment’. The other common ore, realgar (As4S4), occurs as bright orange-red crystals or powder, whence it is sometimes known as ‘ruby of arsenic’. The name ‘realgar’ (otherwise ‘rizagal’, ‘rosaker’ or even ‘rose-alger’) comes from the Arabic meaning ‘dust of the cave’.4 It was also known as ‘sandarac’, which probably comes (via Greek) from an ancient Iranian word.

According to Prof. Mercuriale, Galileo’s friend and mentor in Galileo’s Revenge, these natural ores ‘grow spontaneously in mines, and arsenic of this sort is said to occur in Caria [in SW Turkey] and also in Pontus [in NE Turkey]’5

In addition, apart from these two natural forms of arsenic – the yellow and the red, if you will – there was another synthetic form, ‘white arsenic’. But I’ll come back to that in a minute.

2. Ratsbane and tetters

Both the naturally-occurring arsenic ores have been widely used as pigments, and realgar was used in fireworks – to produce white light, oddly. But, if you were a painter using these pigments, you definitely didn’t want to lick your paintbrush.

Pigments for sale at a market stall in Goa, India. Wikipedia

According to Emsley (p.95), eating or drinking 250mg of arsenic in one form or another would be enough to kill most people; less would be needed if they were young, or old, or sickly. That is a very small amount, about 1/120th of an ounce.

Many other animals are also vulnerable to arsenic. Not unreasonably, therefore, arsenic has been widely used throughout history as an insecticide and pesticide, in particular to kill rats and mice. The glossary to a 1543 book of surgery, for example, states that ‘Realgar is made of brimstone, unslaked lime and orpiment. It killeth rats’.6 Hence ‘ratsbane’ (i.e. ‘bane/curse of rats’, or rat-poison) was the popular name for orpiment and, especially, realgar in Elizabethan times.

Clearly rat-poison in this form was well embedded in popular culture. Shakespeare’s near-contemporary the playwright Robert Greene (1558-92) wrote, rather unsympathetically, that ‘The mouse, if she feeds upon rose-alger [realgar] for the glistering hue, deserveth to be poisoned’.7 And their fellow dramatist Ben Jonson (1572/3-1637), in a surprisingly early health warning, insisted that ‘A tobacco-pipe…will stifle them all in the end, as many as use it; it’s little better than rats bane, or roseaker.’ 8 (This would be an appropriate moment to read my review of Simon Gray’s Smoking Diaries.)

Somewhat more precariously, arsenic ores were also widely used as ‘a cure for the itch’, that is to say, in powders or creams for the treatment of all manner of skin conditions – for which ‘tetters’ was a handy generic label 9. Thus the ancient Roman herbalist Dioscorides (c.40AD-c.90AD) recommended orpiment ‘to repress “excrescences”, in other words warts and skin eruptions’ (Emsley 94).

And the arsenic ores were applied to animals as well as humans. The late fifteenth-century hunting manual The Boke of St Albans recommends ‘Powdre of orpement blown upon an hawke’. A bit nearer to Galileo’s time, the falconer at the court of the d’Este Dukes of Ferrara purchased ‘powdered orpiment… to get rid of [his falcons’] lice’ (Hollingsworth 50). This is what Giovanni the Huntsman is about when Galileo tracks him down in the stables in Galileo’s Revenge 4.3.

3. Crystal arsenic

Unsurprisingly, some people’s definition of ‘rat’ and ‘pest’ was quite elastic. In early fifteenth-century Tuscany, for example, Cristoforo di Giovanni, aka ‘Cefo’, wants to marry ‘Cristina, a nubile girl of some seventeen years’. Fair enough, but first of all he has to get rid of his wife Angela. (Brucker 142-6). To this end he decided that ‘I will give her rat poison’. When this was only partially effective, he ‘bought some poison called risalgarium and he took this pulverized poison home…’ It doesn’t end well for Angela. Nor for Cefo, I’m pleased to say.

No doubt any number of inconvenient rivals and relatives were disposed of by the judicious administration of powdered orpiment or realgar. But they do have their shortcomings. Both orpiment and realgar are brightly coloured, and insoluble in water (or wine). Thus, although they may be fit to treat infestations of gullible rats and mites, they are less suitable for human pests – a bright yellow sediment at the bottom of your goblet might arouse suspicion, whether before or after consumption.


Stradanus (1523-1605), The Alchemist’s Studio, in ‘Studiolo’ in Palazzo Vecchio, Florence. Figure bottom right is Duke Francesco de’ Medici, a keen (al)chemist.

Fortunately, in the thirteenth or fourteenth century there was discovered – or re-discovered, for it may have been known since Roman times – an artificial compound of arsenic, namely (in modern terms), arsenic trioxide (As4O6). According to Galileo’s medical mentor Mercuriale, this ‘is made from natural arsenic [i.e. orpiment or realgar ore] and salt mixed in equal weight, then burnt in an earthenware vessel until the vapours condense about the [mouth of] the vessel like crystals, from whence this kind of arsenic is usually called crystalline.’ 10 Actually, it was more commonly labelled ‘white arsenic’, presumably to align it with orpiment and realgar as ‘yellow’ and ‘red’ arsenic respectively. This kind of synthetic arsenic, Mercuriale continues, ‘is hot and dry in the fourth degree, nay, indeed, at the very limit of the fourth degree. And, although by reason of these qualities it is exceedingly contrary to our nature, it has in addition a hidden and destructive [occultam & deleteriam] property against us…’

What Mercuriale doesn’t mention is that this new synthetic ‘arsenic’ is slightly soluble in cold water (more so in hot), and that the resulting solution is ‘colourless and almost tasteless; if anything it imparts a slightly sweetish taste to the water’. [Emsley139] So, no bright colours, no odd flavour, no strange sediments.


To be continued in Part 2, in which your villain (or other disgruntled protagonist) will find out where to source the best arsenic, how to administer it most judiciously, and what might be the chances of their crime escaping undetected.

Sources and reading

Brucker, Gene ed. The Society of Renaissance Florence. A Documentary Study (New York, 1971)

Emsley, John. The Elements of Murder. A History of Poison (Oxford, 2005)

Holloway, S.W.F. ‘The regulation of the supply of drugs in Britain before 1868’, in Porter and Teich eds., Drugs and Narcotics in History (Cambridge, 1995)

McElwee, William. The Murder of Sir Thomas Overbury (London, 1952)

Oxford English Dictionary (OED)

White, J.H. Inorganic Chemistry (London, 1962)

  1. With apologies to Raymond Carver
  2. If 100+ seems like a lot of ‘elements’ compared with the much more concise four Aristotelian elements, or the alchemists’ ‘tria prima’, then consider the alphabet.
  3. Think of common salt, for example, which is a compound of sodium and chlorine, neither of which you’d want to sprinkle on your dinner.
  4. See OED ‘realgar’.
  5. Mercuriale De venenis 39r.
  6. See OED ‘realgar’.
  7. Mamillia 1 Wks. II.114.
  8. Every Man in his Humour III. v.
  9. OED ‘tetter’: ‘A general name for any pustular herpiform eruption of the skin, as eczema, herpes, impetigo, ringworm, etc.’ That’s almost Shakespearian: ‘Thou pustular herpiform eruption…’
  10. De venenis 39r. Modern sources (e.g. Emsley 20) suggest ‘natron’, i.e. natural sodium carbonate, instead of ‘salt’. I suspect that simply roasting the arsenic ores on their own would liberate the arsenic trioxide. It was probably first discovered anyhow from the smelting of copper and other metal ores that were contaminated with arsenic. It should be noted that this is a very dangerous procedure because of the poisonous fumes liberated.