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McBain Balance
McBain Balance is a balance which uses the gravimetric method for measuring sorption of various gas or vapors on samples. These measurements provide the data required to determine surface area, and water/vapor sensitivity of materials.

The original balance was introduced by McBain and Bakr in 1926 used a quartz spring in a vacuum apparatus. The displacement of the sample bucket at the end of the quartz spring was measured externally using a surveyor type telescope called a catherometer. Gas or vapor was introduced into the evacuated balance and the displacement measured. Either the sample section or the entire sorption balance was in a temperature control environment. Vapors can be used if the liquid reservoir is kept a lower temperature than the sample.

Modern sorption balances use beam vacuum electron micro-balances (e.g.Cahn Instruments). On one side of the beam is suspended the sample and on the other side is suspended the counter weight. The current required to maintain the beam horizontal is directly related to the weight change of the sample during the sorption experiment. --MatLab (talk) 14:59, 25 February 2008 (UTC)