Prefiguring the Arsenic Wars

David S. Caudill

The Arsenic Wars

The term arsenic wars usually refers to toxicological debates between Parisian academics in the first half of the 19th century. This was a time when arsenic detection techniques progressed from a collection of relatively unreliable precipitation and reduction tests to the more substantial methods devised in 1836 by the British chemist James Marsh and in 1841 by both Swedish Jöns Jacob Berzelius and German Hugo Reinsch.

By the 1830s French toxicologist Mateu Orfila (1787– 1853) was a medical celebrity in Paris and abroad, the dean of the Paris Faculty of Medicine, as well as a frequent forensic expert. He was actively involved in the highly publicized 1840 trial of Marie Lafarge, who was accused of poisoning her husband with arsenic. Orfila’s authoritative detection of arsenic in the corpse, and his disagreement with other experts who found no arsenic, sent Madame Lafarge to prison and set off a debate around Europe about arsenic detection.

The Lafarge affair offers a picture of numerous tests and practices for arsenic detection and disagreements over their conclusiveness, prior to gradual acceptance of the Marsh test. Local physicians in the case had first relied on autopsies and symptoms, while Orfila encouraged chemical analysis and was critical of “smell” tests (e.g., attributing a “garlicky” odor to arsenic). Orfila, however, was also critical of the initial chemical tests, which led investigators to confirm the presence of arsenic on the basis of ambiguous colors. As a result of the growing popularity of the new Marsh test, three pharmacists employed it several times and found no arsenic.

But doubts remained, and Orfila was called on to reapply the Marsh test—he confirmed that arsenic was present and that it did not come from the chemicals used in his analysis or the earth from which the victim’s body was exhumed. These qualifications were important because critics had pointed out that zinc used in the early Marsh test could contain arsenical impurities and that cemetery soils could contain arsenic.

Orfila was accused of hubris in his tests by François-Vincent Raspail (1794–1878), a frequent challenger of Orfila’s methods in trials and in scientific publications. Raspail raised concerns about the presence of arsenic in copper vessels used to boil cadavers and in the paint on the wood used to transport them. He viewed Orfila as too theoretical and experimental for the practical life-and-death concerns of the courtroom. In addition Raspail reflected on the difficulty of opposing Orfila in the courtroom, given Orfila’s fame and ability to decide university appointments and dismissals. Orfila’s role as a skeptic and as a critic of the overconfidence of the initial experts in the Lafarge trial was, in Raspail’s view, eclipsed by Orfila’s own overconfidence and blindness to the limitations of his toxicological experimental methods.

The Lafarge trial was a sensation in Europe, and Orfila’s celebrity caused international interest in the scientific procedures. Orfila’s reception in Britain was generally positive, but his hubris was a concern. Despite Orfila’s obvious brilliance, he seemed to overreach himself, to be too enthusiastic. Orfila’s British critics saw him as sacrificing the restraint required of a courtroom expert. In his textbooks the famed British toxicologist Alfred Swaine Taylor (1806–1880) referred to Orfila as an example of immodesty—of confidence even when the results of his arsenic-detection techniques were ambiguous.

Taylor himself, however, was soon accused of overconfidence in his work with his Guy’s Hospital colleague George Owen Rees on the trial of William Palmer in 1856. Palmer was a country physician suspected of poisoning his wife, his brother, and his gambling partner, John Parsons Cook. Taylor testified on the basis of clinical evidence that Cook had been poisoned by strychnine, even though the poison was not detected.

Defense witnesses argued that a skilled analyst would have detected any strychnine present, and criticism continued in the popular press. Taylor defended himself in part by recalling Orfila’s sins of excess in the Lafarge case, claiming that his own critics, like Orfila, had inflated the capacity of chemical analysis. Nevertheless, despite Taylor’s successful efforts to reframe the Palmer case in his textbooks, his public image suffered, and he was condemned by some for his scientific pretentiousness. Three years after the Palmer trial Taylor testified in the arsenic-poisoning case of Thomas Smethurst; on the basis of a single result using the Reinsch test he declared the presence of arsenic and Smethurst was convicted. (In Reinsch’s test arsenic forms a metallic coat on a copper leaf treated with nitric acid when it is placed in a heated solution of hydrochloric acid and arsenic.) However, William Herapath, a Bristol toxicologist, later showed that Taylor’s use of the test was faulty and Smethurst was pardoned.