The head of the sperm whale contains 3-4 tons of spermaceti, a substance valued as a lubricant for fine machinery and a component of automatic transmission fluid. It is also used in making ointments and fine, smokeless candles (once it solidifies into a white wax upon exposure to air). Physeter catodon has also been a target of commercial whaling in years gone by, notably in areas around the Gulf of Mexico. The meat of the whale is not generally consumed. Instead, spermaceti is extracted from the head, and the teeth are often used as a medium for the artistic form of engraving and carving known as scrimshaw. The most important product obtained from giant sperm whales is the oil once used as fuel for lamps and now used as a lubricant and as the base for skin creams and cosmetics. A gummy substance called ambergris forms in the large intestines of sperm whales and can be found floating on the surface of the water or washed ashore once it is expelled. It was once believed to have medicinal qualities, but it is now used in connection with manufacture of perfumes, based on the fact that when it is exposed to air, it hardens and acquires a sweet, earthy smell. The island Ambergris Cay, just south of the Gulf of Mexico, was given its name because of the great quantities of this substance gathered along its shores.