[21] This anticipates a little the development of poisonous gases. Some of these forms were not in use until 1917.
[22] This is the main principle. It is to be remembered that new devices are constantly being experimented with and put into use on the front.
[23] The Allies refrained from using asphyxiating gases for several months, but by 1918, they had attained superiority in their use.
[24] First used in the spring of 1917.
[25] This gas was a development of 1918; it is known as gas vesical.
[Transcriber's Note:]
Retained some inconsistent hyphenation (e.g. gun-fire vs. gunfire).
Added missing umlauts to "Würtemberg" in multiple places.
Page v, changed "in not" to "is not."
Page vi, changed "L'illustration" to "L'Illustration" and "Le Monde Illustré" to "Le Monde Illustre" for consistency with image captions.