A Portable Precision Salinometer for Use with Small Samples

A portable salinometer for use with small bottle samples is described. It is based on the continuous flow principle used in our precision laboratory salinometer. However, (1) it is not thermostatted, instead it has two cells in the same bath and measures the conductivity ratio of sample to standard seawater at the same temperature; (2) the water is drawn from the sample bottle by suction instead of driven by pressure; (3) the required sample is less than 1/10 that of the laboratory model so that standard water can be used continuously as reference; (4) there is no contamination of the rest of the sample, almost the whole of which is available for other measurements. The reading circuit operates on 100-200 Hz square wave current and determines the ratio of conductivity of the measured sample to standard seawater at the same temperature directly. Appropriate trims are provided to compensate for cell constant differences and deviation of the standard seawater from exactly 35 0/00 S.