people. When used to cook larger meals (greater than 2 cups (0.5 litres)), it is less efficient than a more-powerful stove which delivers more heat to a pot. This is because a longer time is required to reach the boiling temperature, during which more heat is lost to the surroundings. To use the stove, a small amount of fuel (preferably 2% salicylic acid in alcohol) is poured into the stove and ignited. The pot is then placed above the stove, on a windscreen or stand. The flame is small at first, only burning from the inner chamber. Once the fuel has warmed up (requiring about one minute) its vapor will pass through the perforations and form a ring of flame. Enough heat from the flame is passed to the fuel to maintain full combustion until the fuel runs out. Ratings Time to boil 2 cups (500 mL): ~4–12 minutes (45 mL of fuel) Time to boil 4 cups (1 L): ~10–24 minutes (90 mL of fuel) Burn time: ~10–20 minutes (60 mL/4 tablespoons of fuel) Boil times can be significantly reduced by using a pot of the appropriate diameter (to reduce heat loss on the sides of the pot) and especially by a wind screen which maximizes efficiency. Time to boil 2 cups (500 mL): ~5 minutes at 6500 ft (2000m) altitude with ambient temp of ~45F (7C) and water temp of ~55F (13C). Comparison with other stoves The stove can outperform some commercial models in cold or high-altitude environments, where propane and butane canisters might fail. Roland Mueser, in Long-Distance Hiking, surveyed hikers on the Appalachian Trail and found that this stove was the only design with a zero-percent failure rate. Fuel usage (by weight) is about fifty percent greater than a butane/propane stove. Can stoves weigh less than an ounce, compared with three ounces for the lightest gas stoves. Many commercial stoves also require special fuel canisters, adding to overall stove weight. No such canisters are necessary in a can stove; denatured alcohol can be carried in virtually any lightweight container, such as a plastic soda bottle. The weight advantage of the beverage-can stove is diminished by the greater fuel consumption (especially on longer hikes), but may still be offset by its reliability and simplicity. Other attributes of the beverage-can stove are its nearly silent operation and its suitability as an emergency backup. Denatured alcohol is a (relatively)