<P> The cremation occurs in a crematory that is housed within a crematorium and comprises one or more furnaces . A cremator is an industrial furnace that is able to generate temperatures of 870--980 ° C (1,600--1,800 ° F) to ensure disintegration of the corpse . A crematorium may be part of a chapel or a funeral home or may be an independent facility or a service offered by a cemetery . </P> <P> Modern cremator fuels include oil, natural gas, propane, and, in some areas like Hong Kong, coal gas . However, coal and coke were used until the early 1960s . </P> <P> Modern cremators have automatically monitor their interior to tell when the cremation process is complete . The time required for cremation varies from body to body, and, in modern furnaces, the process may be as fast as one hour per 50 kg (100 lb) of body weight . </P> <P> A cremator is not designed to cremate more than one human body at a time; cremation of multiple bodies is generally illegal in the United States and many other countries, though exceptions may be made for (for example) still - born twins, or a baby and mother who died during childbirth . </P>

Where did the practice of cremation come from