Objections to German Type Mask
The American Gas Service felt from the beginning that a design which attached the box of chemicals to the facepiece was unsound in principle (this design was used in the German mask and in the French A. R. S. masks), since it did not allow proper flexibility for increasing the size of the box to care for new gases. Furthermore, the weight of the box during movement caused the facepiece to swing slightly from side to side. This interfered with vision and tended to lift the facepiece away from the face and allow gas to enter. That the objections of the American Gas Service to this type were correct was proved by the difficulty encountered toward the end of the war by both the French and the Germans in trying to provide a suitable filter for protection against particulate clouds and the smokes, such as stannic chloride and diphenylchloroarsine.