Of all the violin and cello makers throughout history, none has achieved the mystique of Antonio Stradivari, the Italian luthier who constructed the Stradivarius violins from spruce, maple and willow. An 18th-century Stradivarius violin, of which a few hundred exist, can fetch millions. The instruments’ value attracts admirers and thieves alike. Stradivari had a contemporary, a fellow northern Italian named Giuseppe Guarneri, who came close: Guarneri violins, also produced in the early 1700s, remain popular among expert players as well.

These 300-year-old violins have, in all likelihood, received more scientific scrutiny than any other family of musical instruments. In a new study published in late December in the Proceedings of the National Academy of Sciences, chemists at National Taiwan University evaluated tiny bits of maple scraps from four Stradivarius instruments and one Guarneri.

Behind that Stradivarius je ne sais quoi, the authors of the new paper suggested, was a bath: the lost art of giving violin and cello wood an extended chemical soak. “This type of chemical seasoning was an unusual practice,” the scientists wrote, “unknown to later generations of violin makers.”

It was not possible to determine who would have conducted such a treatment. But the researchers had a hunch that Italian wood sellers bathed their lumber — before the violin makers began their work — to stave off worms and rot.

The mineral bath, coupled with three centuries’ worth of high-frequency vibrations, could have altered the wood fiber structure. “In their current state, maples in Stradivari violins have very different chemical properties compared with their modern counterparts, likely due to the combined effects of aging, chemical treatments and vibrations,” concluded the Taiwanese scientists.

“This paper is the first to convince me that some type of mineral infusion into wood might cause superior sound in a musical instrument,” said Henri Grissino-Mayer to Steph Yin in The New York Times. Mr. Grissino-Mayer, a University of Tennessee tree expert, was not involved with the current research.

Several other researchers previously explored the violins’ chemical composition. Some have gone beyond it. A Minnesota radiologist ran a loaned Stradivarius through a CT scanner to look at its inner anatomy. The brief cooling period in Europe, the Little Ice Age that lasted from the 1300s through the 19th century, altered the growth of the harvested spruces, Mr. Grissino-Mayer and a colleague theorized in 2004. And an instrument built out of modern lumber will resonate in a manner indistinguishable from a Stradivarius, one Swiss researcher argued in 2012, if you first treat the fresh wood with certain fungi.

Such scrutiny has a flip side — a concern that the minute examinations of the Stradivarius and Guarnerius only serve to further hype the instruments.

Two University of Salford acoustic scientists in England, writing at the Conversation, argued it was possible that a psychological phenomenon called the halo effect was the source of the instruments’ perceived better sound. The pair cited a 2012 report in which 21 violin experts, during a blind experiment (a musical Pepsi Challenge of sorts), preferred playing a modern instrument over an authentic 18th-century Italian one. Perhaps the Stradivari glamour is the orchestral equivalent, in other words, of paying extra for Tylenol when popping generic acetaminophen blunts a headache just as well.

Still, more than a few violinists maintain that the Stradivarii are instruments par excellence. To The Washington Post in March, Joshua Bell (a professional violinist, and the virtuoso behind a 2007 L’Enfant Plaza stunt in D.C.) likened playing a well-made violin versus a Stradivarius to the difference between a “very good tenor” and the late Luciano Pavarotti.

“When you play a Strad, a great Strad,” Mr. Bell said, “there’s something about it.”

For Stradivarius skeptics, though, the debate is hardly settled. “The problem with studies looking at chemical composition is that they don’t include measurements of how the violins actually vibrate and create the sound waves which we hear,” the Salford scientists argued at the Conversation.

As the Taiwanese scientists wrote, too, the “acoustic effects associated with the specific chemical alterations observed in this study remain to be investigated.” To make such science sing, future research will have to show the mineral differences are welcomed by our ears.

First Published: January 3, 2017, 5:00 a.m.