ON CHEMICAL WARFARE. 401 



held in position by elastic bands over the head so as to make an airtight joint 

 round the face. Tlie wearer breathes in and out through the mouthpiece, the nose 

 being closed by a clip attached to the mask. Air is drawn in through an inlet 

 valve at the bottom of the container, and any poisonous gas is absorbed during 

 its passage through the charcoal and granules. The expired air passes out 

 through an exit valve, the inlet valve closing in order to prevent expired air 

 passing out through the container and causing deterioration of the contents. 



Ihe type of box respirator adopted by the Germans differs from ours, as the 

 box containing the chemical absorbents is attached directly to the mask and no 

 mouthpiece is used. The efficiency of the appliance depend.s therefore on the 

 tightness of the joint between the face and the edge of the mask, and on the 

 good condition of the latter material. If the mask does not fit the face or if 

 it has been punctured, air containing gas passes direct to the lungs of the wearer 

 and he becomes a casualty; whereas if the British mask is damaged the wearer 

 continues to breath through the mouthpiece and tube, and he is safe except 

 for the possible effect of the gas on his eyes. Also the British method of 

 carrying the box of chemicals in a haver.sack on the chest, instead of attaching 

 it directly to the mask, enabled us to use a larger box which gave a higher 

 stiindard of protection, and it was a comparatively simple matter to add an 

 extension to the British respirator if necessary. For instance, in April 1917 

 a small metal extension containing cotton wool was added at the bottom of each 

 container to give increased protection against smoke particles such as those 

 produced by the vaporisation of stannic chloride in air. 



In August 1,917 this extension was embodied in the improved ' N.C. Con- 

 tainer ' in which specially activated wood charcoal was substituted for animal 

 charcoal, and layers of cellulose wadding added to stop smoke particles. The 

 ' N.C. Container ' continued in iise until the Armistice, and its standard of pro- 

 tection was so high that there were no instances of men being gassed owino- to the 

 failure of a respirator wliich was in a serviceable condition. Wher^s the 

 earliest pad respirators only gave protection for a- few minutes against concen- 

 tration of chlorine of the order of one part in 10,000 parts of air, the 'N.C. 

 Container,' when new, protects its wearer for half-an-hour or longer against one 

 part of phosgene in 100 parts of air. 



Work of the Gas Services. 



In addition to the chemists who were working during the war in the research 

 and supply departments and in the Special Brigade, a considerable number were 

 employed in the various theatres of war and at home in advising commanders 

 on technical matters connected with gas warfare, and in training and instructing 

 the troops in gas defence. Their work, which was essential to our success in 

 gas warfare, has not hitherto beeit generally known or appreciated. The problem 

 of gas defence is not solved by devising a suitable respirator. It is necessary 

 to train men very carefully in its use, and to give them sufficient information 

 about the behaviour of gases, in order to make them understand the best methods 

 of protecting themselves against gas, and to remove the ignorance which i.s the 

 chief cause of their alarm. The instruction given at the many gas schools which 

 were formed^ during the war was of vital importance in giving men confidence 

 and in reducing the number of casualties, and enabled us gradually to reduce the 

 disadvantage under which we suffered in consequence of the general lack of 

 scientific training among all ranks. 



In France the Chemical Advisers and Divisional Gas Officers had particularly 

 responsible posts. In addition to their advisory and instructional duties, they 

 played an important part in the organisation of the gas defence of ' their 

 formations. It was their duty to investigate every enemv gas attack, to devise 

 means of improving our defence, to collect blind gas shells for examination, 

 and to collect evidence of the results of our own gas operations. All new 

 appliances were sent to them for trial before they were adopted, and the rapid 

 progress of our defensive measures would have been impossible without their 

 criticism and advice, as they were in constant touch with front-line conditions, 

 and could see how far the appliances were likely to meet present and future 

 needs. 



