a friedrichs condenser (sometimes incorrectly referred to as "friedrich's" condenser), a spiraled finger condenser, was invented by fritz walter paul friedrichs, who published a design for this type of condenser in 1912. it consists of a large, spiraled internal cold finger-type capillary tube disposed within a wide cylindrical housing. coolant flows through the internal cold finger; accordingly, vapors rising up through the housing must pass along the spiraled path.