Foams are slightly more dense than airs and they are generally made with a similar liquid, but foamed up in a cream whipping device charged with nitrous oxide.

• 泡沫比空气的密度要大，而且它们通常是由一种相似的液体组成，但是在充满一氧化二氮的冰淇淋装置里会起泡沫。