Gas projectiles can be used in all types of country. Woods, bushes, corn fields and clumps of buildings may hold the gas active for a considerable time.
Two kinds of shell gases are used by the enemy, viz., lachrymators, which mainly affect the eyes, and poison gases, which may affect the eyes and are just as deadly as the gases used in the form of clouds.
(1) Tear, Or Lachrymatory Shells:
These shells on explosion drive the liquid chemical which they contain into the air as a mist. They cause the eyes to water strongly and thereby gradually put men out of action.
Their actual smell may be slight. Large concentrations of lachrymators begin to affect the lungs and cause sickness, coughing and general irritation.
(2) Poison Shells:
Besides the comparatively harmless lachrymators the enemy also uses projectiles which contain a gas, the action of which is very similar to that of phosgene. Because of their slight detonation, these shells are liable to be mistaken for blinds, but they emit large quantities of a gas which attacks the lungs strongly and is very dangerous, and even in slight cases may cause serious after effects.
(3) Smoke:
The enemy may make use of smoke, either in the form of a cloud or emitted from shells and bombs. Smoke may be used with gas or between gas clouds; it may also be used alone to distract attention from a real discharge of gas, to cover the advance of infantry, or merely as a false gas attack.
(4) Mine And Explosion Gases: