What is a specific weight?
Specific weight usually refers to the density of the material compared to the water density. This number is listed as a ratio, which means that there are no units in the discussion. By using a known specific weight for a particular substance, it is possible to determine what sample of the substance is pure or how concentrated it is. In some industries, the density of two substances can be compared to each other instead of water in determining a specific weight.
In most cases, the specific weight is determined as the ratio of the density of a certain substance compared to the density of the same amount of fresh water at 39 degrees of fahrenheite (4 degrees Celsius). At this temperature, fresh water with the greatest density, which is 1 gram per milliliter. A substance with a specific weight lower than the substance water floats on water, while the object with a higher specific weight sinks. Temperature and atmosphere pressure will change the specific weight of the substituent, so standard specific gravity values are determined at this temperature and at one atmospherean era of pressure, which is the air pressure on the sea level.
In addition to standard measurements of specific weight, it is also possible to compare two density substances instead of comparing them with water density. Many different industries use their own sets of density comparison that help them control concentration. When testing gas density, air is often used as standard and liquids and solids are often tested against water, even if other liquids can be used. It is also possible to measure a value known as the apparent specific weight of the substance by creating the weight ratio of the same volume of the substance and reference substance as water.
The concept of specific weight was discovered by a Greek scientist and inventor, Archimedes. When Archimedes was commissioned to determine whether the new crown of the king was made of fixed gold, she found that he could take the crown and the same mass of solid gold and see if two displacedIli the same amount of water from the tub. Soon after this discovery, the densities of a number of different substances were calculated so that it was easy to determine their purity. It is also possible to take an unknown substance and experimentally determine its density compared to water to narrow the possible materials from which it could be made.