(1) Rotary furnaces can use any carbon source such as coal, coke, or ebonite as reducing agent, and they can use a variety of fuels, such as oil, coal, or gas.(2) All flutes, for example, whether they are made of glass, ivory, ebonite , or metal, or whether they have a duct, are classified as 421.(3) The first synthetic material to be used in flute-making was ebonite , also known as vulcanite.
