Benzene is normally drawn as a hexagon with alternate single and double bonds. This while useful for understanding its chemical reactions it does not properly represent the reality.

Investigation shows that all 6 carbon-carbon bonds in benzene are identical in length and properties. This is due to the aromatic nature of Benzene where the electrons for the second bonds are delocalised into hybrid orbitals above and below the level of the flat benzene ring.

Benzene is also very useful for throwing over things and setting fire to them in Call of Cthulhu games. As in:

"Is that a bottle of benzene in your pocket or are you just glad to see me?"

This is how my character Benzene Bob the Mad Machete Missionary got part of his nickname.

I think the advice originally suggesting this as an essential CoC accessory came from "The Handbook of the Theron Marks Society".