Franklin's pulse glass: Two glass bulbs and tube containing ether.

Franklin's pulse glass: Two glass bulbs and tube containing ether. The apparatus consists of two glass bulbs, with a glass connecting tube, containing ether. The glass vessel is supported on a pivot at the center of the connecting tube. The lower bulb is thus positioned near a small electric heater. The warmth from the heater causes rapid evaporation of the ether in the bulb close to it, and this produces sufficient pressure to force liquid into the higher bulb on the opposite side. The heater at the opposite side now warms ether as the vessel tips to the opposite side. The motion continues to recycle. TEMPERATURE AND EXPANSION