“Flue-curing [a process accidentally invented by Stephen, a slave in Caswell County in 1839] turned tobacco a bright ‘lemon yellow.’ Many commented on the mildness of this tobacco and its particular suitability for cigarettes. But what they could not have known is that this process also subtly changed the chemistry of the leaf to make it slightly acidic rather than alkaline…..
“Smokers soon found they could take cigarette smoke deep into their lungs, rather than holding the smoke principally in their mouths as they did with pipes and cigars. In this way — as we now know — nicotine absorbs rapidly into the bloodstream; some seven seconds later it reaches the brain. Nicotine addiction was born…. This physiological process would create a mass industry and a consequent epidemic of tobacco-related diseases.”
– From “The Cigarette Century: The Rise, Fall and Deadly Persistence of the Product the Defined America” (2007) by Allan M. Brandt