Exposure Time (days)

Electrode Potential (mV)

pH of Environment

Concentration of mineral salt medium in mil/litre

0

−0.550

7.0

500

7

−0.661

6.8

510

14

−0.672

5.0

520

21

−0.710

5.0

525

28

−0.710

5.0

530

35

−0.712

4.0

530

42

−0.710

6.0

535