State's attorneys resume cross-examining a tobacco scientist today in Minnesota's tobacco trial. R-J Reynolds head of product development David Townsend testified yesterday his company added ammonia to cigarettes to improve flavor; the state claims the industry used ammonia to hook smokers by giving cigarettes a stronger nicotine kick. Minnesota public radio's Elizabeth Stawicki reports: Townsend repeated a defense theme that tobacco companies add ammonia to cigarettes for a smoother, chocolate-like flavor. He said R-J Reynolds began adding ammonia to its camel filters in 1974 to gain market share from highly successful Marlboro manufactured by Philip Morris. State's attorneys acknowlege ammonia d