Mercury is a nerve toxin. Mercury switches are used in thermostats, "silent" light switches, clothes washer lids and chest freezers. A mercury switch is usually present when no mechnical switch is visible.
It is illegal to put mercury - containing products in the trash.
Keep the mercury intact and bring it to a household hazardous waste collection site for free. If you spill mercury, do not vacuum it up. Immediately call the Minnesota Pollution Control Agency at 651-649-5451 for proper cleanup procedures, or visit the U.S. Environmental Protection Agency.