The chlorinity of water is defined as the mass of chlorine equivalent to the total mass of halogen contained in 1 kg seawater. It is determined by the Mohr-Knudsen titration, which however neglects fluoride.
The halogen concentration of sea water can be expressed in terms of chlorosity which is the number of grams of chloride and chloride equivalents to the bromide in one liter of sea water at 20 °C (68 °F).
Chlorinity is related to chlorosity as,
Chlorinity(o/oo) - chlorosity/density
Chorinity is related to salinity as,
Salinity(o/oo) = 0.03 + 1.805 x chlorinity