Favourite poisons in 1920s crime fiction

Poison was a popular method of committing murder in 1920s and 1930s crime fiction. These are the decades considered to be the Golden Age of Detective Fiction.

Authors such as Dame Agatha Christie, Margaret Allingham, Gladys Mitchell, Dame Ngaio Marsh, Dorothy L Sayers, Patricia Wentworth, Josephine Tey would despatch their victims with some lethal concoctions.

“Give me a decent bottle of poison,” Agatha Christie once said, “and I’ll construct the perfect crime.”

Christie used poison in her books more than any other murder method. It was a subject she was familiar with, having trained as an apothecary’s assistant. She passed her exams in 1917 after receiving private tuition from a local commercial pharmacist.

During the First World War, Christie spent time as a nurse and worked in the local hospital dispensary. When it came to drugs, she understood dosages and dispensing techniques.

Cyanide

Cyanide was Agatha Christie’s particular favourite, and it featured more than any other poison in her novels, although she was also known to employ arsenic, strychnine, digitalis and morphine.

Cyanide works quickly, and a high concentration will kill in minutes. It can be inflicted as a colourless gas or in crystal form.

Cyanide is derived from the seeds of the Prunus family and can be found in plants such as cassava, lima beans and almonds. Pits and seeds of apricots, apples, and peaches can contain substantial amounts of chemicals that metabolise to cyanide. The edible parts of these fruits contain much lower amounts of these chemicals.

Christie used cyanide in her novels Sparkling Cyanide, The Mirror Crack’d from Side to Side, And Then There Were None, and A Pocketful of Rye.

Arsenic

Arsenic was another favourite because it was so easy to obtain at that time. Arsenic was commonly bought in chemists as people would use it to make their own weedkiller and rat poison. The chemist would ask you to sign the poisons register when you bought it, so there would be a record of the purchase.

Arsenic was used in all sorts of products, including the inks and aniline dyes of printed wallpapers and clothing until as late as the 1920s. It was present in food colouring and beauty products such as arsenic complexion wafers that promised pure white skin.

Arsenic is a natural element widely found throughout the environment in the air, water and land. The biggest risk to public health comes from contaminated groundwater. Inorganic arsenic is naturally present at high levels in the groundwater in many countries.

As a tasteless and odourless white powder, arsenic is minimally soluble in cold water but dissolves easily in hot fluids such as tea or cocoa. The symptoms of arsenic poisoning include watery diarrhoea, causing dehydration and hypovolaemic shock. If it results in hepatic and renal impairment, there may be a garlic smell to the victim’s breath.

The beauty of arsenic as a poison in crime fiction novels is that the symptoms of ingesting arsenic can be similar to those of other ailments. However, when a body is subjected to toxicological examination, arsenic is traceable.

In a famous case, a solicitor, Harold Greenwood, was accused of murdering his wife by arsenic poisoning. Her cause of death was certified by a doctor as heart disease. However, when Mabel Greenwood's body was exhumed, no evidence of heart disease was found, but 0.25 to 0.5 grains (16 to 32 mg) of arsenic was. See my post: The Mysterious Poisoning of Mabel Greenwood.

Arsenic plays a significant part in the plot of Agatha Christie’s 4.50 From Paddington.

Strychnine

Amazingly, it’s over 100 years since Christie’s first published novel, The Mysterious Affair at Styles, hit the bookshelves, and Hercule Poirot made his first appearance. Strychnine was the poison of choice for Christie in this novel.

Strychnine certainly produces a dramatic impact. 15 to 60 minutes after swallowing strychnine, the victim can have symptoms of agitation and apprehension or fear, depending on the dosage they’ve ingested. Other symptoms can include restlessness, uncontrollable arching of the neck and back, rigid arms and legs, jaw tightness and painful muscle spasms that can lead to fever and kidney and liver injury.

Strychnine is a strong poison, and only a small amount is needed to produce severe effects. It comes as a white, odourless, bitter crystalline powder that can be taken by mouth, inhaled, mixed in a solution, or injected directly into a vein.

Today, strychnine is used primarily as a pesticide, particularly to kill rats.

As well as arsenic, strychnine, and cyanide, Christie used eleven other poisons in her books, including hemlock, thallium and taxine. Derived from the leaves of the English yew tree, taxine was used to good effect in the novel A Pocketful of Rye.