In a gas thermometer, pressure varies linearly with tempurature (at fixed volume), and is given by P=aT+b, in degrees celsius. One can determine the value of absolute zero by calibrating the gas thermometer at non-extreme temperatures and extrapolating the calibration curve to the point of zero pressure (and hence zero temperature).
Fill gas thermometer with air by opening the valve all the way, then close the valve tightly to seal the bulb. Place the bulb of the gas thermometer into a water bath of known temperature and record pressure and temperature. Repeat procedure with at least one more bath of a different temperature. Plot data, and extrapolate to zero pressure to determine abs zero. To test accuracy of calibration curve, use gas thermometer to determine temperature of LN2. Should get something close to -196 degrees Celsius. (However, oxygen will liquify, causing P vs T curve to become non-linear. So, may not get exactly -196.)
All thermo lab supplies are located in L35, sections G and H. Saftey glasses are in section C1.