The first use of poison gas on the Western Front was on 22 April 1915, by the Germans at Ypres, against Canadian and French colonial troops. The initial response was to equip troops with cotton mouth pads for protection. Soon afterwards the British introduced the Black Veil Respirator, which consisted of a long cloth which was used to tie chemical-soaked mouth pads into place. Dr. Cluny MacPherson of the Royal Newfoundland Regiment brought the idea of a mask made of chemical absorbing fabric and which fitted over the entire head to England, and this was developed into the British Hypo Helmet of June 1915. This mask offered protection to the eyes as well as to the respiratory system. One British officer described it as "a smoke helmet, a greasy grey-felt bag with a talc window certainly ineffective against gas". This helmet had two celluloid eyepieces, but there was no way to expel the carbon dioxide build up inside the mask . This type of mask went through several stages of development before being superseded in 1916 by the canister gas mask the PH helmet. This had a mask connected to a tin can containing the absorbent materials by a hose and an outlet valve to reduce the carbon dioxide build up inside the mask.