Diphenylaminechloroarsine is called Adamsite and it is a riot control agent, not a nerve gas.
It is intended to incapacitate but not kill. There were FAR more toxic gases around in those days that were used in the First World War such as phosgene and mustard gas.
Sarin is another step up again. Comparing the use of a riot control gas in 1919 (one year after the mass gassings of the Western Front) to the use of sarin against civilians in 2013 is ridiculous journalism.
