
Platinization and Platinum Black
5. Platinization and Platinum Black
Only the electrodes having constants from 5 to 50 must be replatinized if the
Before platinizing, clean the cell with detergent and brush as described in Section 4.1.
Support the cell in a cylindrical vessel with the end of the cell raised from the bottom. It is not necessary to remove the cell from the fittings for platinizing. However, the guard tube must be removed from the low constant cells. Pour in platinizing solution (p/n 31103011) to a level above the
To platinize the 5, 10, 20, 25 and 50 constant cells, immerse an auxiliary platinum electrode* in the solution to a point about midway between the
ATTENTION
*This third electrode should be chemically pure platinum. Its shape is unimportant. It may be one of the electrodes in another conductivity cell or a platinum strip, sheet, rod, wire, etc.
Connect the positive terminal of the battery to the auxiliary platinum electrode. Note the time in seconds listed in Table 4.2. During the platinizing operation, move the cell up and down gently to keep the solution stirred. Then disconnect the battery and remove the cell. Rinse the cell thoroughly in tap water and then rinse in distilled water.
Pour the platinizing solution back into its container as it may be used a number of times.
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