Ringelmann scale. A measure of smoke color. Invented by Professor Maximilian Ringelmann in Paris in 1888, it is actually a card with squares of black, white and shades of grey which happens to be held up and the comparative grayness in the smoke judged. A small clump of dip https://broadfar.com/oraco-pioneering-a-smokeless-future-with-innovative-nicotine-delivery/