Popular terror of gas--Necessity for drilling and early personal experience--Sure defence from gas possible--The first gas alarms--The prussic acid scare a myth--The phosgene scare a reality--The helmet made to combat it--Necessity for renovating the helmet. The final object in the training of men in defence against gas is that troops shall be able to protect themselves completely and as quickly as possible in all the multitudinous circumstances in which they may encounter the poisonous gas in the field. To attain this it is necessary to inspire confidence by letting them in as far as possible on the principles underlying the use of gas and the tactics which are adopted by the enemy; and, secondly, to bring their practical proficiency and discipline up to such a standard that they make the very best use of the apparatus that is given to them. It must be remembered that one of the greatest difficulties in talking to people about gas is the mystery of it. Even educated people hardly understand the word “gas” in connection with war and are apt to think of coal gas and dentists’ gas in consequence. The result is that the gas of the Germans was sometimes credited with all sorts of impossible qualities of movement and deadliness, and it can hardly be realised what alarm and distrust may exist in the raw recruit with regard to gas until he has been given some instruction. This is even as great a danger as the over-confidence of the veteran soldier, who may know just as little about it. Mere drilling and assertion are not sufficient to inspire confidence and acquire proportion, and it was realised very early that personal experience was needed. To gain this arrangements were made for every man to see and smell gas in concentrations that would at any rate produce severe discomfort if dwelt in for any length of time, and for each soldier subsequently to be exposed to gas while wearing a gas helmet in such a concentration that negligence in obeying orders or in using the smoke helmet correctly would lead to real danger to life. By this means confidence could be inspired in everybody, though there is always a certain danger due to recklessness among the more adventurous types.