This part of JB/T 6237 specifies the method for the determination of the pH value of the aqueous solution of silver powder for electrical contact materials, which is applicable to the range of pH4~ pH10. The principle of the method is to soak the silver powder in water, boil it with heating and then filtrate, and determine the pH value of the filtrate. The reagents include pH Meter calibrate solution and buffer solution. The instruments are acidity meter and thermostatic Magnetic Stirrer. The sample is weighed 50.0g, and the pH value is determined by calibration, blank test and determination steps. Precision requires that under different laboratories and operators, the absolute difference of the results of two independent tests should not be greater than the specified value.