Ringelmann scale. A measure of smoke color. Invented by Professor Maximilian Ringelmann in Paris in 1888, it is basically a card with squares of black, white and shades of gray that's held up along with the comparative grayness of your smoke judged. : to inhale and exhale the fumes https://broadfar.com/oraco-pioneering-a-smokeless-future-with-innovative-nicotine-delivery/