The oysters are nucleated with a bead composed of mother-of-pearl and a small piece of mantle tissue. This bead becomes the nucleus of the pearl and is the reason akoya pearls are more often perfectly round.
Carbon definition, Chemistry. a widely distributed element that forms organic compounds in combination with hydrogen, oxygen, etc., and that occurs in a pure state as diamond and graphite, and in an impure state as charcoal.
Carbon tetrachloride is a colorless organic compound with the chemical formula CCl4. The International Union of Pure and Applied Chemistry (IUPAC) name for this chemical is tetrachloromethane. Carbon tetrachloride is often used as an organic solvent, a fuel additive, a catalyst, a refrigerant or a metal de-greaser. Prolonged exposure to this chemical can be harmful to the liver, kidneys and central nervous system. At room temperature, carbon tetrachloride is a colorless liquid. Its molecular weight is 153.8 grams per mol. The melting point of this compound is minus-9.4 degrees Fahrenheit (minus-23 degrees Celsius), and the boiling point is 170 degrees Fahrenheit (76.7 degrees Celsius).