Re: fire

Karl,

The name for what you see is COMBUSTION.

That's a three syllable word for fire. When you squeeze the lemon peel, some of 
the oils that give lemon its characteristic flavor and fragrence squirt out, 
hit the flame and burn up.

The oil is called limonene [see the resemblance to lemon?] and is a dimer of 
isoprene, the basic building block of the molecule in natural rubber.

After lemons are harvested for their juice, the peel is further processed to 
extract the limonene, which has valuable commercial uses in, for example, 
adhesive [sticky] tape.

When you are old enough, and so inclined, you might try a Martini cocktail and 
the bartender will ask if you want it with an olive garnish or a "twist" --- 
the latter refers to a slice of lemon peel that has been twisted to release the 
essential oil, limonene, to flavor the drink.

Good observation!

Ken