<P> Even at Second Ypres, Germany, still unsure of the weapon's effectiveness, only issued breathing masks to the engineers handling the gas . At Ypres a Canadian medical officer, who was also a chemist, quickly identified the gas as chlorine and recommended that the troops urinate on a cloth and hold it over their mouth and nose . The first official equipment issued was similarly crude; a pad of material, usually impregnated with a chemical, tied over the lower face . To protect the eyes from tear gas, soldiers were issued with gas goggles . </P> <P> The next advance was the introduction of the gas helmet--basically a bag placed over the head . The fabric of the bag was impregnated with a chemical to neutralize the gas--however, the chemical would wash out into the soldier's eyes whenever it rained . Eye - pieces, which were prone to fog up, were initially made from talc . When going into combat, gas helmets were typically worn rolled up on top of the head, to be pulled down and secured about the neck when the gas alarm was given . The first British version was the Hypo helmet, the fabric of which was soaked in sodium hyposulfite (commonly known as "hypo"). The British P gas helmet, partially effective against phosgene and with which all infantry were equipped with at Loos, was impregnated with sodium phenolate . A mouthpiece was added through which the wearer would breathe out to prevent carbon dioxide build - up . The adjutant of the 1 / 23rd Battalion, The London Regiment, recalled his experience of the P helmet at Loos: </P> <P> The goggles rapidly dimmed over, and the air came through in such suffocatingly small quantities as to demand a continuous exercise of will - power on the part of the wearers . </P> <P> A modified version of the P Helmet, called the PH Helmet, was issued in January 1916, and was additionally impregnated with hexamethylenetetramine to improve the protection against phosgene . </P>

World war 1 gas warfare tactics and equipment