CHEMICAL  & ENGINEERING NEWS – One hundred years ago last month, Allied forces stood their ground in Ypres, preventing the larger and better-equipped German army from taking control of that strategic town in western Belgium. The following spring, Germany attacked again in the Second Battle of Ypres, gassing thousands of French colonial troops with chlorine. That infamous event, which marked the first major use of poison gas as a weapon, introduced the world to the devastating effects of modern chemical warfare. The attack also sent scientists and manufacturers scrambling to develop protective gas masks. Continue