Mercury is sensitive to changes in temperature.  It was used for thermometers for many years. 

Recognizing Mercury Thermometers

They have silvery liquid in them, not red or blue.  Digital thermometers do not contain mercury, except those that have a small amount in the battery. 

Routes of Exposure

Broken thermometers can cause extensive cleanup.  They contain about 20 times the mercury of a fluorescent light bulb/ lamp.

Thermometer Recycling

Several County Health Departments accept mercury thermometers and exchange them for a new electronic thermometer.  Look at the list of Local Health Departments and ask in your area or call 1-800-RECYCLE for recycling locations.