Polarograph
Use
The quantitative and qualitative analysis of the species contained in a dissolution. It identifies and measures their concentrations from intensity curves.

Description
A polarograph is essentially an electrolytic cell, so it has necessarily to be formed by:
An electrode of mercury drop type, which is a very fine capillary tube through which mercury flows slowly and at a constant speed. This comes in the form of small drops.
A reference electrode, which can simply be a mercury deposit or a standard electrode of calomel or platinum.
Another electrode, to which the dissolution of the electroactive substances, which we want to analyze, is added.
So that we can obtain the intensity curves, we have to add:
A power supply, which let us provide the cell with a variable potential.
A microammeter to measure the amperage generated during the electrolysis of the electroactive substances.