Non-mercury Outdoor Thermometer
Instead of mercury, this thermometer uses pigmented mineral spirits which have proven to be just as accurate as mercury thermometers. Mineral spirits include a variety of compounds, and are derived from light distillate fractions from the crude oil refining process. Spirit gauge thermometers rely on the principle that liquids expand when they are heated and contract when they are cooled. This type of thermometer consists of a reservoir for the liquid, the bulb, connected to a very narrow tube. The narrow tube accentuates the very small changes in the liquid's volume that occurs when the temperature of the liquid changes.
Guaranteed for Life!