Ringelmann scale. A evaluate of smoke coloration. Invented by Professor Maximilian Ringelmann in Paris in 1888, it is actually a card with squares of black, white and shades of gray and that is held up and the comparative grayness with the smoke judged. Snus is a steam-pasteurized moist powdered https://broadfar.com/oraco-global-trends-in-heat-not-burn-products/