24 August—Petrichor finally appeared yesterday. Don’t bother looking it up. It’s the smell of rain—the distinctive, earthy scent that frequently accompanies the first rain after a long period of dry weather. More precisely, it’s the name of an oil that’s supposedly released as an aerosol from the earth into the air before rain begins to fall. That’s right, before the rain begins to fall. Yesterday, Zeus gave us just over an inch of rain, along with lots of thunder.

Zeus? Who else? According to Greek mythology, Zeus is the god of rain and thunder, after all. Of course, he’s also the king of gods, the Greek pantheon, who rules from Mount Olympus. And the word petrichor comes from the Greek πέτρος (petros) “stone” and ἰχώρ (ichor), the ethereal blood of the gods. In Greek mythology, to be sure.

The word petrichor was coined by Dick Thomas, a chemist who had recently retired from Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO), in a paper published with Isabel Bear, who was still working there, in “Nature” in 1964. Isabel (Joy, to her friends) and Dick described it in simple terms:

“The diverse nature of the host materials has led us to propose the name ‘petrichor’ for this apparently unique odour which can be regarded as an ‘ichor’ or ‘tenuous essence’ derived from rock or stone. This name, unlike the general term ‘argillaceous odour’ avoids the unwarranted implication that the phenomenon is restricted to clays or argillaceous materials; it does not imply that petrichor is necessarily a fixed chemical entity but rather it denotes an integral odour.”

Got that? Argillaceous odour indeed. Argillaceous means “consisting of or containing clay.” In other words, clayey. And the title of the paper that christened petrichor was “Nature of Argillaceous Odour.” Given all the hardpan under most of Litchfield, I’m surprised yesterday’s petrichor wasn’t more argillaceous. Then again, Zeus didn’t give us that much rain to get down to the clay.

Getting back to ichor, it’s not really blood as we know it. Rather, it’s the ethereal fluid—the tenuous essence, as Dick Thomas so beautifully put it—that flows through the veins of the Greek gods and immortals. It’s the very stuff that makes them immortal. On the other hand, ichor is toxic to humans, killing us instantly if we come in contact with it. So we must be careful where and with whom we tread. Therefore, just to be safe, keep away from Mount Olympus.

On the subject of humans, ichor is also the smelly watery discharge from wounds and sores, probably so named by some smart-ass atheist physician in ancient Greece.

And then there’s geological ichor, a fluid emitted by magma that causes granitization of rock. But we won’t go there. It’s too hot . . .