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The Spheroidal State

المؤلف:  GEORGE A. HOADLEY

المصدر:  ESSENTIALS OF PHYSICS

الجزء والصفحة:  P-274

2025-12-29

650

 Whenever water is thrown upon a very hot metallic surface, a condition called the spheroidal state is set up. The effect of the heated surface is to vaporize a little of the liquid, so that the remainder does not rest directly upon the metal, but upon a cushion of steam. This by its constant movement keeps the liquid in rapid vibration. The liquid takes the globular form because of surface tension, and changes into vapor at a rate faster than evaporation and slower than boiling. If the metal cools and the liquid comes in contact with it, a sudden production of steam is the result. Steam boiler explosions have resulted from the water in the boiler getting low, and then cold water being suddenly turned on after the boiler had become red-hot above the water line.

Demonstration. - Place a smooth tin or brass plate upon a tripod and heat it with a burner. Drop a few drops of water upon it with a pipette. After the spheroidal condition is set up, remove the flame and let the plate cool. …..