A mercury-filled Celsius thermometer with a range of 0°C-100°C can be used for most purposes. At a minimum, the scale should be subdivided into 0.1°C. Thermometers are calibrated for total or partial immersion. Total-immersion thermometers must be completely immersed in water to yield the correct temperature. Partial-immersion thermometers must be immersed only to the depth of the etched circle that appears around the stem just below the scale level. For best results, the accuracy of the thermometer in routine use should be checked against a precision thermometer certified by the National Institute of Standards and Technology.