Thursday, March 28, 2019

The weight of water

It's the UN's international year of the periodic table, so I've been writing and thinking about the elements. While writing a piece for Nature Chemistry about the hidden depths of the periodic table (the more than 3000 isotopes that could be stacked onto their elemental spots), I wandered across an interesting set of papers on heavy water and isotopic tracing, which along with some questions my students had in the intro chem course led to another piece for Nature Chemistry (The weight of water).

Heavy water (D2O) is water where the hydrogens have been replaced with deuterium, an isotope of hydrogen that weighs about twice as much as standard hydrogen. Heavy water weighs just over 10% more than regular water, a tablespoon weighs only about a gram more, so it is probably not noticeable should you heft a glass of it.  (Heavy water was a key element of some nuclear weapons programs, check out the harrowing story of the raids on a Norwegian heavy water production facility in WW II.)

In one of the papers I read, future Nobelist George de Hevesy stuffed some twenty (albeit tiny) goldfish into 60 ml of water, in another he reports drinking heavy water and making thousands of distillations of urine to recapture the water, measure its density and track deuterium through the human body.

Drinking your experiement sounds dicey, but in small amounts heavy water is safe to drink, and as I recently learned, used in human metabolic studies in doses of about 10 ml. An interesting question raised in the papers I read was about the taste of heavy water. One report suggests a burning sensation might be felt when drinking it, another (by Harold Urey, who discovered deuterium) suggests it tastes like undeuterated water. But other reports say it tastes sweet.

With a bit of help from my youngest son, I set up a repeat of Urey's blind taste test. And was surprised to find I could indeed taste the difference. It is sweet.

And for the next few weeks, until the last of the extra deuterium clears my systems, I'll be just a little bit heavier than usual.

Shameless self-promotion, George de Hevesy is one of the Catholic scientists featured in the audio series I did last year with Brother Guy Consolmagno, SJ, the director of the Vatican Observatory.

Tuesday, March 26, 2019

Done is good.

There is a saying at Bryn Mawr, "Done is good." A way of reminding students (and ourselves) not to hang on to a project beyond its time, that the enemy of the good is sometimes the perfect. And also a reminder to celebrate what has been finished, that to finish something is itself an accomplishment.

The book of Lenten reflections I have been working on for the last six months is done, the last of the copy edits made and sent off. And it is good. At least I hope it is good!  But it has been nice to begin to clear up my office, to re-shelve the books (a selection of the books that I referred to in the text are in the photo: Augustine, Eliot, Levertov, Ignatius....). It's a chance to clear physical space to work, but also the mental space this writing has been holding in my brain.  To be done is a good thing.

So I should celebrate...a dinner out? a good movie with Math Man? A long walk? So many things I could do — but most of all what I crave is more time to read....books! I'm midway through Radium Girls, Kate Moore's compelling read about an industrial accident that played out in slow and awful motion, and have ordered Balaam's Donkey to dip in and out of.