The sprayers previously mentioned were originally suggested for use against the gas cloud itself, the idea being that chemicals should be sprayed at the cloud so as to neutralise the poisonous gas and thereby purify the air. Nearly everybody with even a nodding acquaintance with chemistry wrote in suggesting ammonia for this purpose, oblivious of the fact that the chemical reaction between chlorine and ammonia in these circumstances produces a dense cloud which is most irritating to the eyes and throat, and that this together with the excess of ammonia would be almost as bad as the original gas. In any case it is impossible to deal with the gas cloud by spraying, because of the enormous amount of chemicals and apparatus that would be required to neutralise the attack. A cloud of chlorine from one thousand cylinders, for example, would require more than forty tons of the strongest ammonia solution obtainable to kill all the gas, even if none of the spray were lost in the ground. Besides this the spraying might have to be continued for hours, some of the attacks having lasted intermittently for more than three hours. It was quickly seen that this was an utter impossibility, but experiments showed that a spray of the hypo solution was quite capable of removing what remained of the gas cloud out of trenches and shell holes and from dugouts into which the gas had penetrated. This of course applied only to chlorine. Arrangements were therefore made for supplying a large number of these sprayers, which are exactly the same as those used for spraying fruit trees and potatoes with fungicides, and men were specially trained in their use so that they could be employed after an attack was over. These men were officially known as the “Vermorel sprayer men,” and were popularly supposed to preface all their operations with the words “Let us spray.” The solution to fill the sprayers was kept in all the trenches in corked rum jars, and there were many amusing incidents rising out of the dual purpose to which these revered vessels were put. It is stated that a certain battalion on going into the line for the first time saw these rum jars safely ensconced in niches in the parapet and immediately thought that they contained the rum ration concerning which they had heard so much before they came out. Some of the more adventurous ones surreptitiously tried out the supposed rum and drank a few mouthfuls of the nauseous liquid before discovering their mistake. The real joke lay in the fact that even after they realised that the liquid was not rum they continued to drink it, and by the time they finished their two days’ tour of instruction there was not a drop of Vermorel sprayer solution left in any of the trenches.