A taste of poison

Why toxic testing wasn’t for the faint-hearted....

TONY HARGREAVES, a lecturer in the schoool of applied sciences at the University of Huddersfield, takes a fascinating look at poisons past and present. But don’t get any ideas...

Tasting the body fluids — and even decaying tissue — from a corpse was once used for detecting certain poisons in the investigation of suspicious deaths.

One well-known case was that of the analytical chemist Thomas Stevenson, a Yorkshireman, examined the dead remains of George Lamson’s brother-in-law, Percy.

Lamson was charged with Percy’s murder and the case was heard at the Central Criminal Court in 1882.

Stevenson, in describing his tests, complained that Percy’s intestines and colon were green with decomposition by the time they arrived at his laboratory.

His tests involved preparing extracts from parts of the dead body and then placing one drop of each on the tip of his tongue.

The results he obtained from the stomach contents, urine and an earlier sample of Percy’s vomit were especially interesting.

A numbing sensation was produced on Stevenson’s tongue. He compared the effect with that of standard poisons kept in his laboratory.

Stevenson concluded that Percy had died from aconite poisoning which led to Lamson being found guilty and sentenced to death.

Aconite poisoning was relatively rare which is probably why a proper chemical test had not been developed.

However, another poison, arsenic, was far from rare and much effort went into finding ways of analysing human remains for its presence.

One reliable test for arsenic became available in 1836 after being developed by James Marsh, the work’s chemist at the Woolwich Arsenal.

It played a crucial role in the trial of Marie Lafarge who stood accused of poisoning her husband with arsenic.

Nowadays, crime investigation relies heavily upon forensic analysis. And poisonings still occur.

The poison, white arsenic oxide, has not altered over the years but the forensic analysis techniques have changed dramatically.

The Marsh test was reliable and sensitive enough to detect minute amounts. It served forensic science well but was eventually superseded by modern analytical instruments.

When a corpse is found, and arsenic poisoning is suspected, it is not simply a matter of testing to see if arsenic is present in the tissue.

A simple “yes” or “no” will not do. The problem is that a certain amount of arsenic is present in all of us.

It comes from the environment and normally does us no harm at all. But if the amount of arsenic present in the body is above a certain level then it is highly suspicious.

The measurement of arsenic in human remains is especially interesting because, when the body is exposed to arsenic, the poison migrates to the hair and nails where it stays.

It is now possible to take a single hair and scan along its length to see if arsenic shows up.

As hair grows at a known rate, the part of it where the arsenic is found can indicate, to within a few days, when the arsenic was taken — or administered. This is important in considering cases of chronic poisoning.

The most powerful of the modern methods is Neutron Activation Analysis (NAA) which can measure the smallest traces in a single section of human hair and without causing any damage to that hair.

NAA was carried out some years ago on hair from the head of Napoleon who was thought to have died from arsenic poisoning.

Arsenic was found in Napoleon’s hair in amounts much greater than the natural level. At first sight, this seemed suspicious and so other evidence was scrutinised.

It was discovered that Napoleon was in the habit of dosing himself with Fowler’s Solution, a solution of white arsenic oxide in bicarbonate.

This was a popular tonic of the day, especially among men who wished to boost their sexual performance. He was possibly also exposed to other arsenic sources.

Portraits of Napoleon standing with his arm inside his tunic are familiar. It is suggested he was actually pressing on his stomach to lessen the pain from some disorder — possibly chronic arsenic poisoning.

His death was certainly due to arsenic but whether it was accidental or through foul play remains unanswered. Today’s forensic analysis methods rely upon a range of advanced instruments for testing body tissue or identifying suspicious substances.

Instruments such as Gas Chromatography Mass Spectrometry (for organic substances) and Atomic Absorption Spectrophotometry (for mineral substances) are now commonly used in forensic science laboratories.

In the teaching of students in forensic science departments, such as the one at the University of Huddersfield, there is much emphasis on how to investigate serious crimes by means of these advanced analysis methods.

Modern methods have, of course, replaced the risky and unpleasant aspects associated with taking samples from a decaying corpse to see if there was the taste of poison.