The first time chemical weapons were used from aircraft was during British operations against Bolshevik forces around Archangel and Murmansk in 1919. It was the result of the ingenuity of a Tasmanian chemist and mining engineer, Thomas Davies (above right) (photo IWM Q 16335).
Below is my article on the episode which was published in the Imperial War Museum Review (No. 12, 1999). (Click each page to enlarge). Scroll to the bottom for more articles.