Dew cells are instruments used for determining the dew point. They consist of a small heating element surrounded by a solution of lithium chloride, which is heated to the point where water is neither being absorbed by or evaporating from the solution. Once this equilibrium point is reached it can be detected by a change in the conductivity of the solution. By carefully regulating the temperature of the solution, the dew point can be calculated. The dew point or dewpoint of a given parcel of air is the temperature to which the parcel must be cooled, at constant barometric pressure, for the water vapor component to condense into water, called dew. ... Lithium chloride behaves as a fairly typical ionic compound, although the Li+ ion is very small. ...