It was an immense relief when the knock of the sergeant on the door summoned them forth and the test was over. And there was great satisfaction when it was learned that all the masks had held and shown that they could be relied on. Once out in the clean, sweet air and under the blue sky that never before had seemed so beautiful, the boys tore off their masks in a hurry. "Now I feel like a respectable member of society and not like one of the Ku Klux Klan!" exclaimed Bart, as he looked around on the flushed bronzed faces of his comrades. "My, but it's good to be out of this hideous rig. I'd like to throw it into the river," he added digging his fingers viciously into the unoffending mask. "You'll be glad enough to have it some day before long," prophesied Frank. "Then you'll count it the best friend you have." "Isn't it pretty nearly time for mess?" asked Fatty Bates wistfully. "Not yet, little one," remarked Billy. "The sergeant's got something else up his sleeve, or I miss my guess." A groan went up from Fatty, which was quickly suppressed when the sergeant looked sternly at him. "Form in single file, men," commanded the sergeant, "and make your way through the trench. Bend over as you go, for you're supposed to be on the enemy front, and not a head must show to be a mark for snipers." They did as they were told, and after they had reached a designated portion of the shallow trench they were halted by their leader. "You're going to be gassed right and proper now," he said. "Some gas shells are going to be thrown over toward you and it's up to you when you see them coming to get those masks on mighty quick." Crouching low and on the alert, the men waited until a gas shell with a hiss and a scream came hurtling in their direction and broke a hundred feet in front of the trench. A cloud of gas came rolling toward them. On went their masks in the twinkling of an eye, and the vapor passed over them harmlessly. Several times this was repeated until the keen eye of the sergeant was satisfied with the dexterity shown by the squad. And there was a general sigh of relief when he summoned them out of the trench and announced that drill was over for the morning. "Phew, but that was some strenuous work," remarked Frank, as holding their masks in their hands the men strolled back in groups of twos and threes toward their quarters. "I feel as though I had been drawn through a knothole," said Fatty Bates. The thought of Fatty being drawn through a knothole was so ludicrous that it provoked a general roar. "I guess we all feel pretty well used up," said Bart when the merriment had subsided, "but all the same it's things like this that are going to help us lick the Huns."