A Chicago musicologist has quietly completed work on a discovery that will make a lot of noise: a hitherto unheard piano concerto by the piano's thundering master, Franz Liszt.

The concerto, tentatively dated from 1839, was identified and assembled from multiple sources over the last nine months by Jay Rosenblatt, a doctoral candidate at the University of Chicago. It is to be given its world premiere next season by the Chicago Symphony Orchestra, with a soloist to be announced.The concert pianist Jerome Lowenthal, one of two pianists thus far permitted to examine the score, said Tuesday: "It's a real work of Liszt, in that it has immediately the thumbprint of that elegant, ironical genius. For anyone who responds to that, this is a wonderful discovery."

The story of the concerto's resuscitation is a classic case study in musical archeology, involving widely dispersed manuscripts, misidentifications by library cataloguers, long slow work and elements of pure chance.

The manuscripts were found in Weimar, East Germany; Nuremburg, West Germany, and Leningrad.

The "new" concerto is in three sections bound together in a single movement, a form pioneered by Liszt, and it is in the key of E-flat major - which caused careless archivists at some undetermined time in the past to mistake some of the manuscripts for an early version of the composer's Concerto No. 1, in the same key.

"Another scholar had speculated that the Weimar manuscript might be a draft for a separate work," Rosenblatt said Tuesday in a telephone interview, "so as much as I'd like to, I can't claim to be the first to notice it."

But as is so often the case in musicology, positive identification and reconstruction depended on a combination of lucky circumstance, intimate knowledge of the piano concertos, and the time and patience to read through the manuscripts carefully.

The Weimar manuscript had been mentioned in 1982 by a Liszt scholar, Michael Saffle, in a list of unpublished materials left at Liszt's death, as "apparently a draft of an otherwise unknown concerto."

(Liszt died at Bayreuth in 1886, but had lived for many years in Weimar.)

It is in the hand of a copyist, and some passages of the solo part are missing. The archivist at Weimar had catalogued the manuscript as belonging to an early version of the familiar E-flat concerto, but examination proved that it had no material in common with that work.

Last April in Budapest, Rosenblatt, gathering materials for a doctoral dissertation on Liszt's music for piano and orchestra, was startled to learn that musicologists there had received from Leningrad photocopies of an early version of the known E-flat concerto, in Liszt's hand - an important document unknown to Liszt scholars in the West. (It had been mentioned, Rosenblatt later learned, in one obscure Russian publication.)

Surprise turned to astonishment when Rosenblatt recognized that interspersed with the pages of the known concerto was also the "new" concerto found in Weimar - but in an infinitely more valuable form, as it was in Liszt's own hand and containing the solo passages missing from the Weimar copy.

"It was shuffled like a deck of cards," Rosenblatt said. "An archivist had gone through and numbered the pages consecutively, but there was no musical continuity between one page and the next; the two concertos were thoroughly scrambled."

The Budapest scholars had not yet examined the materials, and did not know of the Weimar manuscript; Rosenblatt's fortuitous visit provided the missing link.

The solo parts absent in the Weimar copy had been struck out by Liszt; evidently he intended to revise them, and had instructed the copyist to leave them blank.

"But the canceled notes are clearly decipherable," said Rosenblatt. "We may never know how he intended to revise them, but at least we have the first version."

The Leningrad autograph, though, is incomplete. Further research turned up one page of it in Nuremberg, and two more among loose scraps back in Weimar. Even with those, there were gaps, which had to be filled in by relying on the copyist's score.

Among the four sources, every note is accounted for, Rosenblatt said. "It's one of those cases where you had to have every piece of the puzzle," he said.

Once the sources were all in hand last year, Rosenblatt set about making a critical edition of the score, which will be published by Editio Musica Budapest.

Why did it lie so long undiscovered? What seems to have happened, Rosenblatt says, is this:

In 1839, after a decade of teaching, composition and family life with the Countess Marie d'Agoult, Liszt returned to the life of a touring virtuoso and entered the period of his greatest fame as a soloist. At that time, he composed (and-or set in order from previous sketches) three piano concertos, presumably for use on his tours.

"In all three," Rosenblatt said, "the orchestration is fairly primitive and the main interest is concentrated in the solo part."

But Liszt was apparently dissatisfied with the works, as he seems not to have played them; he used concertos by other composers when he appeared with orchestra.

In the 1850s, when he had again withdrawn from the whirl of touring life and was conducting and composing in Weimar, Liszt revised two of the concertos, substantially improving and elaborating the orchestral parts, and these are the two that we know today. The third, left aside for one reason or another, is the new discovery.

Since Liszt never played the three concertos in their primitive forms, nobody knew there was a third one to look for.

"Liszt learned a lot about the orchestra from his first-hand experiences in Weimar," said Rosenblatt, "and frankly, if someone were inclined to touch up the orchestration a bit, I think it would be justified. But it's completely performable just as it is."