"The gas can be produced in large quantities from coal tar besides existing in crystalline deposits," replied Luke Evans. "It is so volatile that I estimate that a single ton will darken all eastern North America for five days. Whereas the concentration would be made only in specific areas liable to attack. The gas is distilled with great facility from one of the tri-phenyl-carbinol coal-tar derivatives." Vice-president Tomlinson was a pompous, irascible old man, but it was he who hit the nail on the head. "That's all very well as an emergency measure, but we've got to find the haunt of that gang and smash it!" An orderly brought in a telegraphic dispatch and handed it to him. The Vice-president opened it, glanced through it, and tried to hand it to the Secretary of State. Instead, it fluttered from his nerveless fingers, and he sank back with a groan. The Secretary picked it up and glanced at it. "Gentlemen," he said, trying to control his voice, "New York was bombed out of the blue at sunrise this morning, and the whole lower part of the city is a heap of ruins." * * * * * In the days that followed it became clear that all the resources of America would be needed to cope with the Invisible Empire. Not a day passed without some blow being struck. Boston, Charleston, Baltimore, Pittsburg in turn were devastated. Three cruisers and a score of minor craft were sunk in the harbor of Newport News, where they were concentrating, and thenceforward the fleet became a fugitive force, seeking concealment rather than an offensive. Trans-Atlantic sea-traffic ceased. Meanwhile the black gas was being hurriedly manufactured. From cylinders placed in central positions in a score of cities it was discharged continuously, covering these centers with an impenetrable pall of night that no light would penetrate. Only by the glow of radium paint, which commanded fabulous prices, could official business be transacted, and that only to a very small degree. Courts were closed, business suspended, prisoners released, perforce, from jails. Famine ruled. The remedy was proving worse than the disease. Within a week the use of the dark gas had had to be discontinued. And a temporary suspension of the raids served only to accentuate the general terror. There were food riots everywhere, demands that the Government come to terms, and counter-demands that the war be fought out to the bitter end. Fought out, when everything was disorganized? Stocks of food congested all the terminals, mobs rioted and battled and plundered all through the east. "It means surrender," was voiced at the Council meeting by one of the members. And nobody answered him. Three days of respite, then, instead of bombs, proclamations fluttering down from a cloudless sky. Unless the white flag of surrender was hoisted from the summit of the battered Capitol, the Invisible Emperor would strike such a blow as should bring America to her knees!