sugars, which are known collectively as "casings". The leaf tobacco is then shredded, along with a specified amount of small laminate, expanded tobacco, BL, RL, ES, and IS. A perfume-like flavor/fragrance, called the "topping" or "toppings", which is most often formulated by flavor companies, is then blended into the tobacco mixture to improve the consistency in flavor and taste of the cigarettes associated with a certain brand name. Additionally, they replace lost flavors due to the repeated wetting and drying used in processing the tobacco. Finally, the tobacco mixture is filled into cigarette tubes and packaged. A list of 599 cigarette additives, created by five major American cigarette companies, was approved by the Department of Health and Human Services in April 1994. None of these additives is listed as an ingredient on the cigarette pack(s). Chemicals are added for organoleptic purposes and many boost the addictive properties of cigarettes, especially when burned. One of the classes of chemicals on the list, ammonia salts, convert bound nicotine molecules in tobacco smoke into free nicotine molecules. This process, known as freebasing, could potentially increase the effect of nicotine on the smoker, but experimental data suggests that absorption is, in practice, unaffected. Cigarette tube Cigarette tubes are prerolled cigarette paper usually with an acetate or paper filter at the end. They have an appearance similar to a finished cigarette, but are without any tobacco or smoking material inside. The length varies from Regular (70 mm) to King Size (84 mm) as well as 100s (100 mm) and 120s (120 mm). Filling a cigarette tube is usually done with a cigarette injector (also known as a shooter). Cone-shaped cigarette tubes, known as cones, can be filled using a packing stick or straw because of their shape. Cone smoking is popular because as the cigarette burns, it tends to get stronger and stronger. A cone allows more tobacco to be burned at the beginning than the end, allowing for an even flavor The United States Tobacco Taxation Bureau defines a cigarette tube as "Cigarette paper made into a hollow cylinder for use in making cigarettes." Cigarette filter A cigarette filter or filter tip is a component of a cigarette. Filters are typically made from cellulose acetate fibre. Most factory-made cigarettes are equipped with a filter; those who roll their own can buy them separately. Filters can reduce some substances from smoke but do not make