Amazon rubber boom the expansion of Iquitos in Peru. The rubber boom occurred largely between 1879 and 1912. There was heightened rubber production and associated activities from 1942 to 1945 during the Second World War. Natural rubber is an elastomer, also known as tree gum, India rubber, and "caoutchouc," which comes from the rubber tree in tropical regions. Christopher Columbus was the one of the first Europeans to bring news of this odd substance back to Europe, but he was not the only one to report it. Around 1736, a French astronomer recalled how Amerindians used rubber to waterproof shoes and cloaks. He
Amount of substance Amount of substance Amount of substance is a standard-defined quantity that measures the size of an ensemble of particles, such as atoms, molecules, electrons, and other particles. It is sometimes referred to as chemical amount. The International System of Units (SI) defines the amount of substance to be proportional to the number of entities present. The SI unit for amount of substance is the mole. It has the unit symbol mol. The proportionality constant is the inverse of the Avogadro constant. The mole is defined as the amount of substance that contains an equal number of elementary entities as there