A partially evacuated glass tube with a bulb at one or both ends and containing a small amount of water or alcohol, which when grasped by the hand exhibits a momentary agitation which is repeated at each beat of the holder's pulse as the heat of the hand vaporizes the liquid.
Origin
Late 18th century.
Definition of pulse glass in US English:
pulse glass
noun
A partially evacuated glass tube with a bulb at one or both ends and containing a small amount of water or alcohol, which when grasped by the hand exhibits a momentary agitation which is repeated at each beat of the holder's pulse as the heat of the hand vaporizes the liquid.