Loss on ignition (LOI) is a test used in inorganic analytical chemistry and  soil science, particularly in the analysis of minerals and the chemical makeup of soil. It consists of strongly heating ("igniting") a sample of the material at a specified temperature, allowing volatile substances to escape, until its mass ceases to change. This may be done in air or in some other reactive or inert atmosphere. The simple test typically consists of placing a few grams of the material in a tared, pre-ignited crucible  and determining its mass, placing it in a temperature-controlled furnace for a set time, cooling it in a controlled (e.g., water-free, CO2-free) atmosphere, and re-determining the mass. The process may be repeated to show that the mass change is complete. A variant of the test in which mass change is continually monitored as the temperature changes is called thermogravimetry.