Lewisite (L) 1917

When You Smell Geraniums…
It’s Lewisite Gas

When You Smell Geraniums…It's Lewisite Gas

Historical background of lewisite

Julius Arhur Nieuwland, a Belgian-born Holy Cross priest and professor of chemistry and botany, made the first known synthesis of acetylene and arsenic trichloride in 1904, during his PhD studies, while conducting a research on acetylene, looking for a solution to synthetic rubber. Over a decade later, in 1917, US Army chemist Winford Lee Lewis developed this arsenical based agent, and named it after his own name – Lewisite.

This blister agent was produced in 1918 to be used in WWI, however the production outcome was late to be used in the war. Nevertheless, it was used to research and develop chemical agent antidotes. In 1940, the Oxford laboratory first synthesised BAL -British anti-Lewisite.

During World War II, the United States, Great Britain, Germany, the Soviet Union, and Japan produced Lewisite. Although chemical weapons were not used in major combat during World War II, the Japanese used Lewisite and mustard gas in China during most of the war years. In addition, more than thirty-five hundred Chinese died in October 1941 at Ichange in the Yangtze Valley after a suspected Lewisite attack.

Any stored Lewisite should be already destroyed, according to the directions of Chemical Weapons Convention, by OPCW.

Commercial use

Lewisite has no use for peaceful purposes in commercial, medical or industrial trades. It has been used only as a Chemical Warfare Agent. Precursor agent arsenic trichloride, is in civil use to manufacture pharmaceuticals.


Lewisite is the main arsenic-based blister agent. When it is pure, it’s colourless oily liquid and it can appear in shades from amber to dark green, or black in its impure form.  Lewisite is odourless when highly pure, but impurities may give it a geranium oil smell – that beautiful flower. Its volatility is higher than that of mustard but still it is low and medium level volatility VOC. It is a persistant type of agent, with a heavier than air feature. 

Lewisite not only affects skin and eyes, but also the respiratory system when inhaled. Lewisite does not have latency time, it affects immediately with a feeling of burning, pain, and later blistering. Poisoning symptoms are mostly the same as other mustards like, immediate eye and skin pain, loss of sight, reddening of skin, itchiness, vesicants, nausea, vomiting, hoarseness, lung edema, fever, eyes and respiratory damage, apathy, depression and systematic long-term damages. Possible consequences from systemic arsenic poisoning, among other symptoms, are: intestinal cramps, vertigo, and liver damage.


Indicators at an unknown incident, where chemical warfare agents like Lewisite are potentially used, are: unexplained odours, low lying chemical clouds, mass casualties, unusual liquid droplets maybe oily, unusual metal debris or delivery equipment, defined pattern of casualties which are different indoors than outdoors, dead animals, and lack of insect life.

Leave area and evacuate the exposed people into fresh air, remembering that Lewisite is heavier than air and it would settle in low-lying areas.  For first responders’, the protection level in an unknown situation is the highest level.  In small spill or leak (less than 200 litres) the initial isolation distance in all directions is 30 meters, and protection distance in day time is 100 meters, changing to 300 meters during night. In large spill/leak (more than 200 litres) the isolation area is 100 meters in all directions, with protection distance of 500 meters during day time, changing 1 kilometre during night. This agent is not flammable.  

Published by Toni Leikas

CBRN Officer (CPT.ret), CBRN Specialist. I'm always wondering, why so many makes and thinks that CBRN is rocket science? It's simple following few basic rules and common sense.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: