Weighing air. Evacuated vacuum chamber being weighed on a mass balance. Before the chamber was evacuated, the mass of the combined air and vacuum chamber was recorded (see C011/1403). Now, after evacuation, a new mass reading is taken. The difference is the weight of the evacuated air. Readings are also taken of the air pressure in the chamber at the start and end of the experiment (gauge at upper centre). The volume of air evacuated (around 900 cubic centimetres) weighed 1.08 grams.
Model release not required. Property release not required.