骨こっ炭たん

noun

bone char; bone black; bone coal

Technical term for a black porous material made from charred animal bones, used as a decolorizing filter or pigment.

• 骨こっ炭たんは砂さ糖とうの精せい製せいに使つかわれることがある。

  Bone char is sometimes used in sugar refining.