Lewisite
Lewisite is an organo-arsenic compound. Pure Lewisite is colourless and odourless. Technical grade of lewisite is a yellow or brown liquid with a distinctive odour that has been described as similar to scented geraniums.
Glossary Source
JRC EU CBRNe Glossary
(
EU Glossary on Chemical, Biological, Radiological, Nuclear, and Explosive risks
)
https://publications.jrc.ec.europa.eu/repository/bitstream/JRC128863/JRC128863_01.pdf