4 O’CLOCK P. M.Further Particular* of the Terrible Explosion at the Arsenal.The cause of the explosion is supposed to have been the ignition of some firework stars which had been prepared for flreworfc9,|and were in a pan near the southeastern window of the building. Several persons who were near by at the time concur in the sttemeni that the stars took lire and in burning Hew out of the pan, some of them felling in and catching to the loose powder where the girls were making cartridges.Major Stebbins, Military Storekeeper, was In the building at the time with several othei gentlemen, and states that after the powder on the benches caught,the lire spread down rapidly, blinding the girls and setting lire to iheli clothes. Many of them ran to the windows wrapped in flames, and on their way communicated the Are to the dresses of others. Fortunately there were no completed cartridge! in the room, those in hand being ready tc pinch.Maj. Stebbens was in a position to assist the unfortunate girls in making their escape, and to him and others who were near, ana to the soldiers and workmen who were promptly oe the spot, do many of them owe their lives.Company F, 6th regiment, Capt. Collins,and D, 19th regiment, Capt. Tyler, V. R.O., wen on the spot promptly, and rendered valuable assistance.