196

BOLOGNA FLASK.

coat, the sudden action of the parts which remained in a state oftension to recover that of perfect expansion, is supposed to effectthe destruction of the mass.

Other philosophers again have been inclined to suspect thatthe phenomenon arises from a quantity of ^air being included inthe substance of the glass which rushes suddenly out, if thesurface which incarcerates it becomes broken. Mr. Lambert,on the contrary, maintains an opinion diametrically opposite tothis : he supposes, that during the sudden cooling'of the glass,vacuities are formed between its particles, and that they aresealed up by the smooth surface of the external covering, so thaton the continuity of that surface being interrupted, the air sud-denly rushing in occasions the bursting of the drop.