Spermaceti (from Greek sperma, seed, and Latin cetus, whale) is a wax that is most often found in the head cavities of the sperm whale (small quantities of spermaceti can be found in the oils of other whales). Spermaceti is created in the spermaceti organ inside the whale's head.Two theories for the spermaceti organ's biological function suggest it either controls buoyancy, or acts as a focusing apparatus for the whale's sense of echolocation. There has been concrete evidence to confirm both theories. The buoyancy theory holds that the sperm whale is capable of heating the spermaceti, lowering its density and thus allowing the whale to float; in order for the whale to sink down again, it must take water into its blowhole which cools the spermaceti into a denser solid. This claim, however, has been called into question by recent research which indicates a lack of biological structures to support this heat exchange, as well as the fact the change in density is too small to be meaningful until the organ grows to huge size.The proportion of wax esters in the spermaceti organ increases with the age of the whale: 38–51% in calves, 58–87% in adult females, and 71–94% in adult males. Spermaceti wax is extracted from sperm oil by crystallisation at 6 °C (43 °F), when treated by pressure and a chemical solution of caustic alkali. Spermaceti forms brilliant white crystals that are hard but oily to the touch, and are devoid of taste or smell, making it very useful as an ingredient in cosmetics, leatherworking, and lubricants. The substance was also used in making candles of a standard photometric value, in the dressing of fabrics, and as a pharmaceutical excipient, especially in cerates and ointments. The candlepower was a photometric unit defined in the English Metropolitan Gas Act 1860 and adopted at the International Electrotechnical Conference of 1883. It depended upon a standardised pure spermaceti candle.