A mid19th century brass salinometer test pot used aboard Royal Navy steam-powered ships.
Height: 29.5 cm.
Diameter of base: 13 cm.
Salinometers were used to measure the proportion of salt in the boiled water in order to prevent the boilers salting up. If through boiling, the proportion of salt in the brine exceeded 2/32, the brine was blown off and new seawater admitted into the boiler. A test pot was used to collect and test the water with a hydrometer.