building.At first it was supposed that the explosion occurred from the steel-pi no hers used m cutting cartridges, striking fire to the cartridges,tint the evidence thus far is to the effect hat it occurred lrom an explosion of rod siar fireworks laid out to dry in the sun on black plates. These fire-works cannot stand a high temperature, and it is believed that the extreme heat of the sun to day exploded them, and that a fuse flew in among the cartridges where the girls were at work, with the disastrous results above noted.Coroner Woodward has gone down to the Arsenal to hold an inquest over the bodies.