All parts of the apparatus are open to the air, and the mercury in the manometer is adjusted so as to come to a fixed mark a.
The substance is now placed on the support already mentioned, and the apparatus closed to the air by inserting the cork at D and turning the cock C. By turning or withdrawing the support the substance enters the bulb; and during its vaporization the free limb of the manometer is raised so as to maintain the mercury at a.
The "receiver" must be connected on the one side to the condenser, and on the other to the exhaust pump. A safety vessel and a manometer are generally interposed between the pump and receiver.
The flask is now partially exhausted, transferred to the cooling bath, and after standing the pressure of the residual gas is taken by a manometer.
How to measure the CVP The CVP is measured using a manometer filled with intravenous fluid attached to the central venous catheter.