The solution is then ready for titration with the standard permanganate solution.
Besides the determination of salinity by titration of the chlorides, the method of determination by the specific gravity of the sea-water is still often used.
Chlorides can be estimated quantitatively by conversion into silver chloride, or if in the form of alkaline chlorides (in the absence of other metals, and of any free acids) by titration with standard silver nitrate solution, using potassium chromate as an indicator.
The reaction of the media must in every case be carefully attended to, a neutral or slightly alkaline reaction being, as a rule, most suitable; for delicate work it may be necessary to standardize the reaction by titration methods.
The titration is complete when the blue colour is so faint that it is almost imperceptible after the flask has been vigorously shaken.