the measurement of changes in weight as a function of changes in temperature used as a technique of chemically analyzing substances

Thermogravimetry (also knows by acronym "TG" and obsolete names thermo-gravimetry, thermogravimmetry, thermography) is a branch of physical chemistry, materials research, and thermal analysis. It is based on continuous recording of mass changes of a sample of material, as a function of a combination of temperature with time, and additionally of pressure and gas composition.