Fall experiments

The alternative energy series continues with wind power, as soon as I slake my curiosity about it enough to stop devouring source articles like James Woods devours candy ("Ooh, piece of candy. Ooh, piece of candy.") and coalesce my chicken scrawl notes. In the meantime, I'm reminded of a fun little home experiment you can do while the leaves are changing.

The colour change of deciduous leaves is related to changing levels of various substances in the leaf, which increase proportionally as chlorophyll (green) decreases. To measure the change in the levels of these funky colours, all you need is some watercolour paper and some ethyl alcohol, and a tree whose leaves are still green.

1. Take some green leaves and crush them in a bowl. Mortar and pestle work best but if not, spoon back and plate can also work. You want to get at least a small amount of paste.
2. Cut a strip of watercolour paper about 4 inches long and 1 inch wide. Using a toothpick, draw a line of green leaf paste across it about half an inch from one end.
3. pour some of the alcohol (regular rubbing, not expensive and drinkable) into a coffee mug, filling it about half a centimetre. You want to have enough so that when you do step 4, the bottom of the paper just touches the bottom of the cup but the alcohol doesn't reach the paste line.
4. Suspend the paper over the cup by taping it to a spoon or toothpick and let the end with the green paste line fall just into the alcohol.
5. cover it so the alcohol doesn't evaporate. Saran wrap works. Make sure the paper's still touching the alcohol.
6. Let sit for a few hours at least, preferably overnight.
7. examine the paper. If you're lucky, you'll see several lines of distinct colour, from the original green upwards that can be pure yellow, or even pure red or orange.

This happens because the various pigments have different solubilities in alcohol (an organic solvent - you can do the same experiment with acetone (nail polish remover but results vary)). They will thus come out of solubility at various stages of the wicking process. The really cool part, though, is that if you're a real egghead and you repeat this maybe twice a week for the next few weeks with leaves from the same tree (and the same part of the tree, preferably) you'll see the bands actually shift, change colour, and grow from mostly green to the various other colours that make up the new pigments.
Tip: If you pick a tree that usually goes orange, you should see some yellow bands and some red bands.

The specs on the colours, their interactions and their solubilities is a fun field for study. Be warned - you'll look at fall colours from now on and annoy friends with expulsions like, "oh, ethylene!"