Critical temperature indicator

摘要

A critical temperature indicator is provided utilizing the volume reduction characteristics of organic compounds as they undergo a change from the liquid state to the solid state. A capillary tube sealed at one end contains a first organic compound adjacent the closed end and a second colored organic compound which has a solidification temperature lower than that of the first compound and which is separated from the first compound by a liquid which is immiscible with either the first or the second compounds. The separating liquid also has a solidification temperature lower than that of the first compound. A colorless or white porous plug is located within the separating liquid and frictionally engages the tube to prevent movement of the plug with respect to the tube. The volume of the separating liquid is such that contact between the colored compound and the plug is prevented prior to solidification of the first compound and solidification of the first compound draws the colored compound into the plug to color the plug and provide a visual indication that the first compound has solidified.