METHODS OF GAS WARFARE 69 



The German apparatus, developed about the same time, 

 is of different pattern, and is still employed. It consists 

 of a small drum, attached directly to the front of the 

 face-piece, and weighs less than the British respirator 

 but must be changed more frequently. It has- no mouth- 

 piece. The chemicals are in three layers: first an inside 

 layer of pumice with hexamethylenetetramine, in the mid- 

 dle a layer of charcoal (sometimes blood charcoal), and 

 outside baked earth soaked in potassium carbonate solu- 

 tion and coated with fine powdered charcoal. 



As regards the future of the gas cloud, it may be looked 

 upon as almost finished. There are so many conditions 

 that have to be fulfilled in connection with it that its use 

 is limited. It is very unlikely that the enemy will be able 

 to spring another complete surprise with a gas cloud. 



The case is different with gas shells. The gas shells are 

 the most important of all methods of using gas on the 

 Western Front, and are still in course of development. 

 The enemy started using them soon after the first cloud, 

 attack. He began with the celebrated "tear" shells. A 

 concentration of one part in a million of some of these 

 lachrymators makes the eyes water severely. The origi- 

 nal tear shells contained almost pure xylyl bromide or 

 benzyl bromide, made by brominating the higher frac- 

 tions of coal-tar distillates. 



The German did his bromination rather badly. As you 

 know, it should be done very carefully or much dibromide 

 is produced, which is solid and inactive. Some of the 

 shells contained as much as 20 per cent, dibromide, enough 

 to make the liquid pasty and inactive. The shells used 

 contain a lead lining, and have a partition across the 

 shoulder, above which comes the T. N. T. and the fuse. 

 These shells had little effect on the British, but one attack 

 on the French, accompanied by a very heavy bombard- 

 ment with tear shells, put them out badly. The eyes of 

 the men were affected, and many of the men were even 

 anesthetized by the gas, and were taken prisoner. 



