After the first German chlorine-gas attacks, Allied troops were supplied with masks of cotton pads soaked in urine; it had been discovered that the urea in the pad neutralised the chlorine. The pads were held over the face until the gas dispersed. Other soldiers preferred to use a handkerchief, sock or flannel body-belt, dampened with a sodium-bicarbonate solution and tied across the mouth and nose, until the gas passed. Soldiers found it difficult to fight like this, and attempts were made to develop a better means of protection against gas attacks. By July 1915, soldiers received efficient gas masks and anti-asphyxiation respirators. Private W. Hay of the Royal Scots arrived in Ypres just after the chlorine-gas attack on 22 April 1915:
