Survey of Chemical Warfare Intelligence

5. Allied interest in the group of nitrogen vesicants, which had already been examined, was revived at the beginning of the war by French work. Later, as a result of intelligence indicating German interest in these compounds, they were again extensively examined. Their advantages were, briefly:(a) Greater effect on the eyes than mustard (b) Very faint smell Their disadvantages were:(i) As an all-round vesicant less potent than mustard (ii) Considerable production and storage difficulties (iii) Counterable by the methods of defence already evolved against mustard.