We present a method of analysis for cross-floats between pressure balances. This analysis relates to the residual mass method of treating cross-float data in which the residual mass M_(e) of one pressure balance is an unknown in the analysis, along with the effective area and the elastic distortion coefficient. M_(e) is the effective mass of any unweighed parts of the piston and load and may include an equivalent mass for other forces on the piston such as oil surface tension. Two models for the analysis with the M_(e) method are presented in a form suitable for linear least squares analysis: one for the calibration of a pressure balance and the other for the comparison of two reference pressure balances. This analysis is equivalent to the p-method when M_(e) is known to be zero. Linear generalized least-squares estimation is shown to be convenient for the calculations. A pressure balance calibration is used to illustrate the analysis and the associated uncertainty evaluation.
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