What type of thermometer should be used to measure the temperature of liquids?

A liquid-in-glass thermometer or a digital food thermometer is the most appropriate choice for measuring the temperature of liquids. These thermometers are specifically designed for accuracy and ease of use in liquid environments. A liquid-in-glass thermometer utilizes the expansion of liquid (often mercury or colored alcohol) to gauge the temperature, providing a clear and precise reading. On the other hand, digital food thermometers can quickly give an accurate temperature reading, making them very convenient for liquid measurements.

In contrast, infrared thermometers are excellent for measuring the surface temperature of foods but do not penetrate liquids adequately, which can lead to inaccurate readings. Dial thermometers may not always provide the responsiveness and precision needed for measuring the temperature of liquids. Although candy thermometers are specifically designed for high-temperature measurements (like those needed when cooking candy), their range isn't always suitable for general liquid temperature measurement. Thus, the combination of accuracy and usability for liquids makes liquid-in-glass and digital food thermometers the best options.