A salinometer is a machine that is capable of measuring the table salt (NaCl) content, known as salinity, of a solution. Another name for a salinometer is a conductivity meter, as dissolved salt in water will increase its ability to conduct electricity at measurable levels. Equipment to measure the salt quantity of water is widely used on ships, so its fitting that the first apparatus to do this was invented by several oceanographers. The Wenner-Smith-Soule salinometer was built in 1930, and, in 1934, it was incorporated into International Ice Patrol Vessels. The International Ice Patrol (ICP) was established in 1914 after the sinking of the Titanic to monitor the movement of icebergs in the north Atlantic Ocean so that further ships collisions could be avoided.
The floatation of freshwater icebergs on the ocean surface is directly affected by its degree of salinity, but this is not the only use for a salinometer. They are also commonly used to measure the salt content of blood, since too much salt in the diet can lead to high blood pressure. The devices are also used on ships that have desalination equipment to purify salt out of water, such as on submarines and cruise ships. A salinometer measurement ensures that the final product of desalination is safe to drink.
The salt content of food can also be measured by a salinometer device through one of four methods. It may have a meter that measures chloride ions in the food and coverts that to a salt content measurement, or a meter to measure sodium ions and do the same. Another approach is to measure the electrical conductivity of the food and convert that to the level of salt present. Finally, a salinometer for measuring salt content in foods that are transparent can measure refractive light qualities by passing a low power laser beam through the food, and convert the readout to the salt quantity present.
Salinometers were originally fairly large, floor-mounted machines. In 1961, Bruce Hamon and Neil Brown, oceanographers in Australia's Commonwealth Science and Industrial Research Organization (CSIRO), developed a portable model that weighed only 33 pounds (15 kilograms). It replaced traditional oil-bath thermostats with a thermistor, which would alter electrical resistivity as temperature changes took place, and it had an accuracy level within 0.003%. Further refinements of the salinometer were done in 1975 by Tim Dauphinee of the National Council of Canada in Ottawa to create a laboratory model that is still widely used as of 2011.