The electric conductance is also able to provide us with indications regarding the quality of the material examined. Those of higher quality reduce the conductance, extracting substances from the water, while the lower-quality ones are even able to increase the conductance, when they release salts (for example phosphates).
How to test conductivity
Execution: The samples of experiment nr. 1 are left untouched for at least two hours at the same temperature (cover the recipients). Then perform the measuring of conductivity.
Interpretation: The good-quality charcoals reduce the conductivity. The worst ones, on the contrary, increase such value, since it will release more abundant substances to the liquid.