“A poison in a small dose is a medicine, and a medicine in a large dose is a poison.”

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Humans appear to have been exposed to arsenic for more than 5000 years and we know this because hair from the Iceman, who was preserved in a glacier in the mountains of the Italian Alps for this length of time, contained high levels of the element. His exposure to arsenic is thought to indicate that he was a coppersmith by trade since the smelting of this metal is often from ores that are rich in arsenic. The arsenic is volatilized as arsenic trioxide and it deposits in the flue of the furnace or on nearby surfaces.

Theophrastus, Aristotle’s pupil and successor and who lived around 300 BC, recognized two forms of what he referred to as ‘arsenic’ although these were not the pure element, but the arsenic sulphide minerals orpiment (As2S3) and realgar (As4S4). The ancient Chinese also knew of them and the encyclopaedic work of Pen Ts’ao Kan-Mu mentions them, noting their toxicity and use as pesticides in rice fields. The mineral realgar was recommended as a treatment for many diseases as well as for banishing grey hair.

Arsenic compounds are also referred to in Democritus’s Physica et Mystica, and the Roman writer Pliny wrote that the Emperor Caligula (12-41 AD) financed a project for making gold from orpiment and while some was produced it was so little that the project was abandoned.

The link between arsenic and gold was not forgotten and arsenic really came into its own in the Middle Ages. Realgar was found to yield so-called white arsenic by fusing it with natron (natural sodium carbonate). Petrus Oponus (1250-1303) showed that both orpiment and realgar could be converted to white arsenic, which we now know as the dangerously toxic arsenic trioxide, and which in the hands of the unscrupulous was to wreak such havoc down the ages. If white arsenic was mixed with vegetable oil and heated it yielded another sublimate, arsenic metal itself, and this may be how the discoverer of the element, Albertus Magnus (1206-80), first made it, although it was not identified as an element until several centuries later. What was also noted in the Middle Ages was that when arsenic was applied to copper metal it turned it silver, and this too appeared to be a kind of transmutation.

Arsenic has a long historical and disreputable pedigree; its very name seems to condemn it as something unspeakable. According to the Oxford English Dictionary the first recorded use of the English word arsenic was in 1310, and certainly it must have been widely known by the end of that century because it was mentioned by Chaucer in his Canterbury Tales, written in 1386. The canon yeoman’s tale has the words:

No need to reckon up the lot,

Rubeficated water, bull’s gall,

Arsenic, sal ammoniac, and brimstone:

And if I wanted to waste your time I could recite any number of herbs.

Rubeficated means red, sal ammoniac is ammonium chloride, and brimstone is sulphur. Later in the tale he mentions orpiment (arsenic sulphide, As2S3) as one of the four spirits of alchemy.

The Romans knew of arsenic materials, as did the contemporary civilizations of China and India. The Chinese used them to kill flies and rodents, and the Indians used them to preserve paper from attack by insects. The Roman writer Dioscorides (40-90) wrote De Materia Medica [Medical Matters] in which he listed scores of remedies, mainly of the herbal kind, but also of the mineral variety and among these he mentioned orpiment and realgar, both of which are natural arsenic sulphides.

Although arsenic rarely threatens our health today, in the past it has affected the lives of many, but that was at a time when it was generally perceived as beneficial, to the extent of being taken regularly as a tonic. Yet while doctors often prescribed it for many ailments, they began to question its widespread use. In 1880 the Medical Society of London published a list of all the products then on sale which were coloured with arsenic pigments, and there were indeed many of them. For example if you were having an evening playing cards, then not only were the cards themselves likely to contain arsenic, but the green baize of the card table certainly did, and the wallpaper of the room would be printed with its pigments, as would the blinds and curtains at the window. The linoleum on the floor might well be coloured with it as would the toys with which the children played, and even the artificial flowers in the vase on the sideboard would have leaves of arsenic green. Arsenic indeed was everywhere.


The forces of the Byzantine Empire, the successor to the Eastern Roman Empire, had at their disposal a wonder-weapon: Greek fire. According to one account it appeared in the reign of Constantine IV Pogonatus (641-68) and its invention was credited to a refugee from Syria who fled to Constantinople after his native land was conquered by the Arabs. Others say that it was really a development of an existing weapon that the Byzantines had used in the 500s but, however it was discovered, it certainly had a profound effect.

Greek fire was invaluable in fighting off the Arab fleets that attacked Constantinople in 673 and 717, and was even used against a Russian fleet in the 900s. In these attacks Greek fire was ejected under pressure from tubes mounted on the prows of the Byzantine ships, rather in the manner of a modern flame-thrower, and it was reputed to catch fire spontaneously and to be impossible to extinguish. Such was the power of this new weapon, and the fear it engendered, that it is thought to have been a significant factor in enabling the Byzantine Empire to flourish for almost a thousand years. The secret of Greek fire was carefully guarded and with the fall of Constantinople to the Turks in 1453 all knowledge of how it was made was lost.

Arsenic as an agent in warfare languished for many centuries until it was revived in World War I. In that war various chemical agents were used in an effort to break through the lines of trenches that stretched for hundreds of miles along the Western Front. The Germans tried chlorine gas on 22 April 1915 and this had a devastating effect on the unprotected British soldiers as it rolled over no-man’s-land and into their trenches. Five thousand men died and more than 15 000 were permanently lung-damaged. In September of that year the British retaliated with mustard gas, a sulphur compound, but the attack was totally ineffective. The disadvantage of these types of chemical agents was that they made the target area unsafe to occupy and it hindered rather than helped the attacking forces. The search was on for ‘better’ weapons.

Several arsenic-based chemicals were found such as Lewisite, Sneeze Gas, and Adamsite, their chemical names being 2-chlorovinyldichlorarsine, phenyldichlorarsine, and diphenylaminechlorarsine. Of these the only one used on a large scale in World War I was Sneeze Gas which was capable of penetrating gas masks and producing unbearable irritation of the respiratory tract. Lewisite was much more potent and this was developed for use as a chemical weapon, but the War was over before it could be deployed. Lewisite is an oily liquid with the odour of geraniums and it boils at the relatively high temperature of 190°C; this means that it is not very volatile and so cannot be used as a gas as such, but it could be spread as a vapour – the ‘dew of death’ – and while it could kill it was more likely to incapacitate because breathing the vapour would cause the lungs to fill up with fluid. The reason for using Lewisite was to disable troops by penetrating their clothing, including protective rubber suiting, causing a violent reaction on the skin forming large painful blisters. On unprotected individuals the chemical would attack eyes, lungs, and skin and eventually lead to liver damage and perhaps death.


The ancient Assyrians of the eighth and ninth centuries BC were familiar with yellow orpiment, and the Greeks and Romans knew that it formed a white compound when roasted, which would be mainly arsenic trioxide. It was also known from an early date that heating orpiment with natron (natural sodium carbonate) produced a product that was deadly and that when it was dissolved in water it gave a clear solution. This reaction would form the soluble salt sodium arsenite, which would indeed have been very poisonous. Thus from the very earliest days there were those who knew the deadly nature of arsenic trioxide and its salts and how to make them. Such knowledge was both dangerous and politically useful, and there were some unexpected deaths that seem likely to have been caused by it. Laws of ancient Rome, dating from around 100 BC were specifically designed to cover cases of death by poisoning.

One of the more notorious poisoners of ancient Rome was Agrippina. She disposed of those who stood in her way, and almost certainly used arsenic trioxide because it was so effective and it enabled her to escape detection. Agrippina undoubtedly murdered her husband in order to be free to marry her uncle, the Emperor Claudius, and thereby gain political power and promote her son Nero into becoming Claudius’s successor. To bring that about Agrippina first eliminated her opponents among the palace advisors, and then poisoned Claudius’s wife Valeria. Once she and Claudius were married she persuaded the Emperor to allow his daughter Octavia to marry Nero. All that remained was to poison the Emperor’s son Britannicus, who would undoubtedly have succeeded him, and persuade the Emperor to name his stepson Nero as his successor. When he did that he sealed his own fate. She poisoned Claudius in 54 and Nero became Emperor at the tender age of 16. Sadly poor Agrippina soon fell out of favour with her son and he had her murdered in 59, although not with poison. Or so the story goes.

The use of poison in the furtherance of political ends is supposed to have reached a fine art in Italy in the 1500s and 1600s. The most notorious practitioners were Cesare Borgia (1476-1507) and his sister Lucrezia (1480-1519) whose names are still synonymous with such depravity. The pair employed a white powder they referred to as La Cantarella and which was almost certainly arsenic trioxide. It was said they got the recipe for making it from the Spanish Moors, and indeed their father was a Spanish cardinal called Rodrigo Borgia who became Pope Alexander VI in 1492. He died in 1503 after attending a banquet with his son Cesare and it was even rumoured that his death was caused by his eating poisoned food and wine that was destined for someone else. This seems unlikely because Cesare was also taken ill, although he recovered. Lucrezia died in 1519 at the age of 39, apparently in a state of grace, having given up her scandalous life for one of religious devotion. Her brother died in a skirmish in 1507 aged 31.

Book of interest


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