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This Chemist's Story Should Become a Movie

Illustration for article titled This Chemists Story Should Become a Movie

James Marsh is an ordinary chemist, just keeping his head down and doing his job. But when he sees a murderer go free, he has to do something crazy. Something like . . . chemistry.


It's possible that John Bodle committed the world's most useful murder. He put arsenic in his grandfather's coffee. He wasn't alone. In 1832, when the murder was committed, arsenic had acquired the nickname "inheritance powder." Arsenic poisoning was not a great way to go. If victims were lucky, they got a headache, got drowsy, and lapsed into a coma. Less lucky victims got vomiting and diarrhea followed by convulsions.

Bodle's case hinged on the testimony of James Marsh, a chemist, who had tested the coffee for arsenic. Unfortunately, the existing test was not particularly sensitive. It involved exposing the suspicious substance (usually a liquid) to hydrogen sulfide. Within a few minutes, a yellow powder would precipitate out of the liquid. This only worked for a few hours. Eventually, the precipitate would disappear, and the liquid would turn clear. A clear bottle did not tend to convince juries. It certainly didn't convince Bodle's jury.

Illustration for article titled This Chemists Story Should Become a Movie

Marsh was angry when Bodle went free. He was even angrier when Bodle outright confessed to the crime once he was out of danger. He was so angry that he spent the next few years developing a test for arsenic that was both sensitive, and would leave him something to show juries.

Marsh's test was just a little more complicated than the existing one, but got an entirely different result. He added zinc and sulfuric acid to the mix. He knew that the zinc would strip away any companions the arsenic might have found, and leave with some extra electrons on its hands. He also knew that, when exposed to acid, this electron-rich arsenic would turn to gas. When gas leaked from the solution, he heated it. Arsenic is a metalloid. Heating the gas and letting that heated gas flow over a glass surface leaves a shiny metal gleam on the glass that doesn't go away.

In 1840, Marsh took his new test to a new trial. Marie Lafarge was accused of murdering her husband with arsenic. The Marsh test showed the jury tangible evidence, and Lafarge was convicted. Unlike Bodle, she never confessed, which gives us a rather bitter ending to the story. Although the Marsh test was so reliable that it was used into the 1970s, many people still believed that Lafarge was innocent, and Marsh was a villain.


[Via The Marsh Test, Forensic Toxicology, Prefiguring the Arsenic Wars.]

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I once retained a lawyer in Boston whose father was a criminal defence attorney in the 50's (long since passed away). The lawyer told me several stories of the incredible lengths his father would go to, to get his clients free (inc. midnight runs to the Canadian border!). I have a chemistry degree so one story stuck out and made my jaw drop.

His father had been retained by a domestic abuse victim who was on trial for murder for eventually cracking up and poisoning her spouse. The investigators had discovered a small bottle of the chemical in her house – Exhibit A. The prosecution brought their expert scientist to confirm what chemical it was and that it was in fact poisonous. At the end of the prosecution attorney's questioning it was his turn to question the scientist.

He asked him if it was true that this chemical had an isomer and to explain what an isomer was to the jury. Having done so he asked the scientist to confirm to the jury that the isomer was in fact not poisonous, which the scientist duly did.

Much to the astonishment of all, he then picked up Exhibit A which was sitting in front of the witness box, opened the top and drank the entire contents. He then said that he had no further questions and sat down. There was of course uproar in the court but there was nothing anyone could really do though I believe his son mentioned he was sanctioned by the judge.

The court recessed for lunch twenty minutes later. He calmly walked out of the court, jumped into a cab straight to his office where his doctor was waiting with a nurse – they pumped out his stomach. Needless to say the wife was acquitted.