Catalytic extraction chamber
A catalytic extraction chamber — also known as a distillation chamber — was a device for cannibalising life energy from others. Magnus Greel, a 51st century human, travelled to the 19th century where he experimented with the device. In setting up the device, Greel had to gauge the strength of the psionic amplification field. He used the sewer rats to test that, and they became giant rats. After that, they were useful as sewer guards. In 1889, he had Li H'sen Chang kidnap woman to be placed in a chamber. Greel hoped to revert the damage done to his DNA, caused by time travel, by distilling their life essence and imbuing himself with it. The Fourth Doctor threw Greel into the device and it sucked out his life force. (TV: The Talons of Weng-Chiang)
