In the early days of urinal cakes, probably around the turn of the 20th century, the little slabs were mostly made of naphthalene, AKA, olden-day moth balls.

大概在二十世纪初的时候，早期的芳香块主要是萘，也就是以前的樟脑丸。

Many urinal cakes these days are made of a compound called a molecule that looks a little bit like a throwing star and is often used as a naphthalene replacement in moth balls.

现在芳香块的主要成分是二氯苯，一种看起来像是飞镖一样的化学分子，通常在樟脑丸中作为萘的替代品使用。