Glass thermometers are widely used in laboratories and industrial fields for accurate temperature measurement. To ensure its accuracy and reliability, regular calibration is necessary. The following are the methods and equipment required for glass thermometer calibration:

**I. Calibration method:**

1. **Comparison method:**

- **Principle:** Compare the glass thermometer to be calibrated with a standard thermometer of known accuracy in the same temperature environment.

- **Steps:**

1. **Environmental preparation:** Select an environment with stable temperature and no airflow interference, such as a temperature-controlled laboratory.

2. **Equipment placement:** Place the glass thermometer to be calibrated and the standard thermometer together in a constant temperature water bath or oil bath with a known temperature.

3. **Temperature stabilization:** Wait for the temperature to stabilize until the reading no longer changes.

4. **Reading comparison:** Record the readings of the two and calculate the difference.

5. **Adjustment and recording:** Adjust the thermometer to be calibrated according to the difference (if possible) and record the calibration results.

2. **Fixed Point Method:**

- **Principle:**Use known physical fixed points, such as ice point (0°C) and boiling point (100°C) to calibrate the thermometer.

- **Steps:**

1. **Ice point calibration:**Immerse the temperature-sensitive part of the thermometer in an ice-water mixture, ensure good contact, read and record the temperature.

2. **Boiling point calibration:**Put the thermometer in boiling pure water, read and record the temperature.

3. **Intermediate point calibration:**Calibration can be performed at other known temperature points (such as the ice water-sodium chloride eutectic point) to improve accuracy.

4. **Compare and adjust:**Compare the difference between the reading and the standard value, make necessary adjustments, and record the results.

**II. Required equipment:**

1. **Standard thermometer:**A thermometer with known high precision and accuracy, used to compare with the thermometer to be calibrated.

2. **Constant temperature equipment:**Such as a constant temperature water bath or oil bath, used to provide a stable temperature environment.

3. **Freezing point reference materials:** Such as pure ice and distilled water, used to create ice-water mixtures.

4. **Boiling point reference equipment:** Such as heating devices, used to heat water to boiling.

5. **Temperature recorder:** Data recording equipment used to record and analyze temperature readings.

6. **Calibration tools:** Such as adjustment screwdrivers, used to adjust the thermometer when possible.

7. **Protective equipment:** Such as gloves, goggles, etc., to ensure safe operation.

**Precautions:**

- **Environmental control:** Ensure that the calibration environment temperature is stable to avoid airflow and temperature fluctuations affecting the readings.

- **Equipment maintenance:** Regularly check and maintain the calibration equipment to ensure its normal operation.

- **Safe operation:** Use protective equipment, especially when handling high or low temperature substances.

- **Record keeping:** Detailed records of the process and results of each calibration for reference and traceability.

Through the above methods and equipment, the glass thermometer can be effectively calibrated to ensure its accuracy and reliability in practical applications.