Adamsite

Adamsite or DM is an organic compound; technically, an arsenical diphenylaminechlorarsine, that can be used as a riot control agent. DM belongs to the group known as vomiting agents or sneeze gases. First synthesized in Germany by Heinrich Otto Wieland in 1915, it was independently developed by the US chemist Roger Adams (for whom it is named) at the University of Illinois in 1918. DM was produced and stockpiled by the Americans at the end of World War I, but never deployed on the battlefield.

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DM is an odourless crystalline compound with a very low vapour pressure. The colour of the crystals ranges from bright yellow to dark green depending on the purity. It is readily soluble in some organic solvents (e.g. acetone, dichloromethane), but nearly insoluble in water. In vaporous form it appears as a yellow smoke.

Adamsite is usually dispersed as an aerosol, making the upper respiratory tract the primary site of action. Although the effects are similar to those caused by typical riot control agents (e.g. CS), they are slower in onset and longer in duration, often lasting several hours. After a latency period of 5-10 minutes irritation of the eyes, lungs and mucous membranes develops followed by headache, nausea and persistent vomiting.

Early battlefield use was intended to be via "Adamsite candles". These were large metal tubes containing Adamsite plus a slow burning incendiary composition. A series of candles were lit and the Adamsite-laden smoke allowed to drift towards the enemy.

DM is regarded as obsolete. It has been widely replaced by more modern riot control agents such as CS which are less toxic and more rapid in onset of symptoms. Even so, DM could still be tactically deployed in combination with an attack of nerve agents. While vomiting the soldier is forced to unmask, thereby exposing him to the lethal agent.

North Korea has been accused of producing adamsite at its Aoji-ri Chemical Complex for stockpiling, although adamsite is weaker than many modern nerve agents, so the reason for this supposed stockpiling is unknown 1.

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