Anything that is soluble will be washed away with the water.
The type of alkali metal used determines the kind of soap product.
Such soaps are also used as thickeners to increase the viscosity of oils.
In ancient times, lubricating greases were made by the addition of lime to olive oil.
Lithium soaps also tend to be hard—these are used exclusively in greases.
Triglyceride is the chemical name for the triesters of fatty acids and glycerin.
The lands of Medieval Spain were a leading soapmaker by 800, and soapmaking began in the Kingdom of England about 1200.
In France, by the second half of the 15th century, the semi-industrialized professional manufacture of soap was concentrated in a few centers of Provence—Toulon, Hyères, and Marseille—which supplied the rest of France.
For example: oil/fat is insoluble in water, but when a couple of drops of dish soap are added to the mixture, the oil/fat dissolves in the water.
The insoluble oil/fat molecules become associated inside micelles, tiny spheres formed from soap molecules with polar hydrophilic (water-attracting) groups on the outside and encasing a lipophilic (fat-attracting) pocket, which shields the oil/fat molecules from the water making it soluble.
Structure of a micelle, a cell-like structure formed by the aggregation of soap subunits (such as sodium stearate): The exterior of the micelle is hydrophilic (attracted to water) and the interior is lipophilic (attracted to oils).
When used for cleaning, soap allows insoluble particles to become soluble in water, so they can then be rinsed away.
Tallow, i.e., rendered beef fat, is the most available triglyceride from animals. Typical vegetable oils used in soap making are palm oil, coconut oil, olive oil, and laurel oil.