An Element of Order
Dmitri Mendeleev and his famous periodic table. (Edgar Fahs Smith Collection, University of Pennsylvania Libraries; Roy G. Neville Historical Chemical Library, CHF)
In an article published in a Russian chemical journal the following month, Mendeleev compared his system to the others he knew about. He believed his system offered eight advantages over competing systems; the possibility of discovering unknown bodies was only a minor one and came second to last in the list. Only in 1870 did he begin to offer detailed predictions—his eka elements—to fill three gaps in the 63 then-known elements.
Meyer’s theoretical daring allowed him to speculate about real, physical atoms but not to predict the existence of a new element. While he did not discount the existence of new elements, he, like other scientists, saw no reason to assume that any gap must be filled with an unknown or even unknowable element. Chemists at the time understood their jobs as explaining substances that already existed. On the other hand, Mendeleev, the filler of gaps, refused for many years to believe in the existence of the atom, hated the idea of radioactivity from the time it was discovered in 1895, and rejected the electron after J. J. Thomson found it in 1897. In addition, some of his elemental predictions were wrong, including one for an element he called Newtonium (see sidebar).
The question of who “discovered” the periodic table first then depends on what people think has been discovered. Says Gordin, “It’s not like, ‘I found this coffee cup first.’ It’s which relationships [that our current periodic table predicts] matter most.” Meyer left gaps. But Mendeleev was the one to say those gaps should be filled. It’s a weird assumption, says Gordin, because no one knew about electrons and protons and neutrons.
A Missed Step
In 1869 censors allowed the publication of the first chemical journal in the Russian language: the Journal of the Russian Chemical Society. But censorship was not the only reason for a lack of Russian science journals. At the time there were about 200 academic physical scientists in the whole of Russia; Berlin, soon to be Germany’s scientific capital, had several times that number.
Mendeleev wrote his textbook, which included his table, in Russian and intended it for Russian college students. Few Russian professional chemists and no chemists outside of Russia would have read it. But Mendeleev also published his table in the first volume of the Journal of the Russian Chemical Society, describing it as a wonderful teaching tool with the added benefit of a few interesting predictions.
“Mendeleev wanted to publish in Russian because he was patriotic and because he was more comfortable in it,” Gordin says. “At the same time, he knew that he wouldn’t get any credit abroad, and credit abroad was very useful for credit at home.” At this time Italian had faded as a language of science, leaving the field to English, French, and German. Russians looking for scientific credit beyond their own borders tended to publish in German or, more rarely, French. Says Gordin, “No chemist in Europe—Italy, France, Germany, Scandinavia, or Britain—read Russian. So if you published it in Russian, it was functionally unpublished. No one would know; it’d have no impact.”
Mendeleev spoke German but wrote that language only haltingly. After he reduced his 10-page article into a one-page abstract, he gave it to a local bilingual professor to translate into German. The professor passed it to a graduate student who quickly translated the abstract; it was published in 1869 in a minor German journal named Zeitschrift für Chemie und Pharmacie, one favored by Russian chemists. Any Germans who wanted to keep track of what Russian chemists were up to read that journal.
Mendeleev understood the need for speed in publishing; coming second counts for little in assigning credit. Unfortunately the translator missed what we now consider to be Mendeleev’s central claim. “There’s a slight mistake in the translation,” says Gordin. “Instead of saying that if you organize elements according to their atomic weight, there is a periodic change in their properties, which is what Mendeleev said in the Russian, the German version says, ‘There is a gradual or a stepwise [stufenweise] change in the property.’ There’s a very easy one-to-one word translation, periodicheski in Russian to periodische in German, but the translator didn’t think it was that important a word.”
Meyer read Mendeleev’s German abstract, and when in 1870 he published his full periodic system in Liebigs Annalen der Chemie, then possibly the world’s most significant chemistry journal, he cited Mendeleev profusely. Meyer added that Mendeleev had almost reached his goal but hadn’t understood that the system was periodic.
Gordin reimagines the response and counter-response: “Mendeleev says, ‘But I said it was periodic,’ and Meyer says, ‘No you didn’t. You said it was stufenweise; you said it was gradual.’ Mendeleev goes, ‘Oh, that was the German abstract. That wasn’t the Russian original. You should have looked at the original.’ And Meyer says, ‘I’m not supposed to read Russian. That’s too much to expect from me. I already have to read Italian and French and English and Swedish!’”