The Chemistry Department and the Hazardous Materials Handling Facility have an inventory of chemicals in their possession. This is a valuable source of information as it lists what is in stock, it can determine what is needed, and can help evaluate whether chemicals have been disposed of in a proper manner. For example, if Chemistry buys 50 litres of a certain chemical, and 20 litres are used in the labs, but only 5 litres are taken to the HMHF by the T.A. then it can be presumed that the remainder has been disposed of improperly. However, neither inventory is completely up-to-date. Without a list, it is impossible to trace how much of a chemical is being used, and how much has been reclaimed.