### Theory:

In few scientific applications, it may required measuring the temperature higher than $$42$$°$$C$$ and lesser than $$35$$°$$C$$; in such cases clinical thermometers cannot be used. We need a laboratory thermometer in such cases.
Laboratory or Lab thermometers are the instruments that are used to measure the temperatures for scientific researches in schools and labs. Fig. - Laboratory Thermometer

Lab thermometers are designed to measure the temperatures, the boiling point and the freezing point of substances. Fig. - Experiment on Laboratory Thermometer

In industries, it is used to measure temperatures higher than what clinical thermometers can measure.

Structure of Laboratory Thermometer:
• It has a long narrow tube (Stem) and bulb compared to the clinical thermometer.
• There is no kink in the Laboratory thermometer.
Temperature Scale in Laboratory Thermometer:
• It has only the Celsius scale ranging from −$$10$$°$$C$$ to $$110$$°$$C$$.
Important!
Precautions to be followed while using a Laboratory Thermometer:
• Do not tilt the thermometer while measuring the temperature. Place it upright.
• Note the reading only when the substance from all sides  has surrounded the bulb.
• Make sure that the bulb should not touch the bottom or sides of the container.
• Do not move the thermometer while doing the measurements.
Difference between Clinical and Laboratory Thermometers:

 Parameter to be compared Clinical Thermometer Laboratory Thermometer Application Clinical Scientific Research and Lab Uses It is used to measure the human body temperature. It is used to find out the boiling point and freezing point of the substances Range $$35$$°$$C$$ to $$42$$°$$C$$ / $$94$$°$$F$$ to $$108$$°$$F$$ $$10$$°$$C$$ to $$110$$°$$C$$ Structure Mercury level does not fall on its own, as there is a kink near the bulb to event the fall of mercury level. Mercury level falls on its own as no kink is present. Working Temperature can be read after removing the thermometer from the armpit or mouth. Temperature is read while keeping the thermometer in the source of temperature, e.g. a liquid or any other thing. Restoration Jerks are given to lower the mercury level. No need to jerk to lower the mercury level.

Reference:
Image credit:
https://commons.wikimedia.org/wiki/File:Lab_thermometer_2.JPG