When I started researching my genealogy, my sister shared with me a family tree she had found on line that took half of my father’s side of the family back six generations, all the way back to Germany in the early 19th Century. As a result, we know more about that branch of the family than any other. I have to admit, though, that it was a little weird to find my own name in this on-line document whose author I had never met (even though she is a cousin). At the root of this tree is my German great-great-great-grandfather (one of them, anyway), who was married three times and fathered 15 children, 9 of whom lived to adulthood. I am a descendant of his second wife, a woman whose maiden name was Kekule.
If you’re a chemist (as I am), the name Kekule might ring a bell. Friedrich August Kekule is the chemist who figured out the structure of benzene, and the story is famous not just among chemists, but also among those who study creativity, because his insight about benzene’s structure came to him in a dream. Benzene, a hydrocarbon solvent (and a carcinogen), is found to have an elemental ratio of one hydrogen to one carbon. It’s quite unusual for hydrogen-to-carbon ratio to be so low. Eventually, the molecular formula for benzene was determined to be C6H6. Once you figure out the molecular formula, you can then play with the atoms as though they were Tinker Toys to figure out what the actual three-dimensional structure of the molecule is. All you have to do is follow the rules of valency: carbon atoms form 4 bonds with other atoms, while hydrogen atoms form just one bond with one other atom. Following these rules, it’s easy to generate potential structures, but there is an additional condition that must be satisfied: Experimentally, it had been found that all of the hydrogen atoms in benzene were equivalent. That is, if you performed a reaction that, say, replaced a hydrogen atom on benzene, the product was the same no matter which of the 6 hydrogen atoms was replaced. While it’s easy to draw structures for a compound with the molecular formula C6H6 following the rules of valency, it’s much harder to find structures where all of the hydrogen atoms are equivalent. So the structure of benzene was a significant problem among chemists in the mid-19th Century.
I will let Kekule himself tell the tale of how he first visualized the correct structure of the benzene molecule, from the translation of an address he gave in 1890:
I was sitting writing at my textbook but the work did not progress; my thoughts were elsewhere. I turned my chair to the fire and dozed. Again the atoms were gamboling before my eyes. This time the smaller groups kept modestly in the background. My mental eye, rendered more acute by repeated visions of the kind, could now distinguish larger structures of manifold conformation: long rows, sometimes more closely fitted together all twining and twisting in snake-like motion. But look! What was that? One of the snakes had seized hold of its own tail, and the form whirled mockingly before my eyes. As if by a flash of lightning I awoke; and this time also I spent the rest of the night in working out the consequences of the hypothesis.
So, in a waking dream of atomic motions, he saw a snake swallowing its tail and subsequently realized that the structure of benzene was a ring! More accurately, the carbon atoms formed a hexagon, with alternating single and double bonds between them, and each carbon was bonded to a single hydrogen atom. The rules of valency are satisfied, and all the hydrogens are chemically equivalent. It was a triumph of Kekule’s structural theory.
Now just because my g-3-grandmother had the same last name does not mean that she was related to him. I needed to find an actual family connection. A big clue that there was a connection was the fact that Kekule was born in Darmstadt. As it happened, that branch of my family was also from Darmstadt, increasing the likelihood of a family connection. Finally, I found a Kekule family tree that confirmed it: My g-3-grandmother was his aunt, which makes him my first cousin four times removed.
So can I credit my heritage with pushing me towards chemistry as a profession? Somehow, I doubt it. No one in my family was even vaguely aware of this connection before I discovered it last year. Plus, with the many generations between us, there’s very little chance that I actually share any genetic material with him at all. But it’s still fun to know that somebody of significance was in my family. It just seems a remarkable coincidence that this person was also a chemist.
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Top Comments (March 29, 2018):
From benny05:
BalanceSeeker demonstrates how Laura Ingraham’s apology tweet makes her moral deficiency apparent. From SeaShell’s recommended post on the subject.
From Araguato (with an assist by belinda ridgewood):
This reply by elwior is the funniest thing I’ve read all day! From Mark Sumner’s front page post on Scott Pruitt’s DC residence.
From your humble diarist:
In reply to a comment by pmc6, Houses in Motion starts a punny thread, with contributions from MrJayRazzle and antirove, and lots of brickbats for Sessions. From Mark Sumner’s recommended post on Mueller’s interest in Sessions’ Russian contacts.
Top Mojo (March 28, 2018):
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Top Photos (March 28, 2018):
Tonight’s picture quilt is courtesy of jotter!