Thermometer
A laboratory thermometer is a tool used in laboratories, places where scientists and science techs perform experiments and measure things.  A laboratory thermometer can measure temperature very closely.  A laboratory thermometer can be put into the liquid or other thing that the scientist wants to measure.  A laboratory thermometer has a long stem with a silver bulb at the end. The silver color in the bulb usually means there is mercury in it.  Mercury becomes bigger as the temperature becomes hotter.  But mercury is a poison to humans.  Mercury-in-glass thermometers are less used in the 21st century because people want digital, alcohol-filled, and organic-based thermometers instead.