In the 1890s at 22 Boulevard de Courcelles in Paris, the young French composer Ernest Chausson lived in a luxurious apartment. Its walls were lined with paintings by Gauguin, Degas and Renoir; and in its salon you could regularly have seen the last two of these as well as the sculptor Auguste Rodin, composers Chabrier, Cesar Franck, Gabriel Fause and the youthful Debussy.

Often there also were the great violinists Ysaye and Thibaud, Alfred Cortot, the pianist, and, from the literary lights of the time, Colette, Mallarme and Andre Gide. And, from time to time, you might also have seen a young composer named Charles Koechlin. This afternoon at 3 in the Renwick Gallery there will be a free concert of music by Koechlin.

It was to this composer that Debussy, sometime in 1911 or 1912, made this extraordinary remark: "Write 'Khamma' yourself and I will sign it!" From a composer of Debussy's stature and achievements at the age of 50, that is an astonishing suggestion. It is true that Debussy was, by that time, seriously ill. Even though he still had another six years to live, walking was already becoming difficult. And "Khamma," a ballet score commissioned from him by the English dancer, Maud Allan, was a venture he took on only because he needed the money. Eventually Debussy finished the piano score, but after orchestrating only the first few measures, he turned it over to Koechlin to complete.

Who, then, is this Koechlin who was held in such high regard by the leading French musicians of several generations, but whose music is still so little known today?

It is easy enough to lay out the basic biographical data: Koechlin was born in Paris on Nov. 27, 1867. At the age of 83, he died in Le Canadel in the region of Var. In between those dates, he studied at the Paris Conservatory, in the famous counterpoint classes of Andre Gedalge, and in composition with Faure, where his fellow students included Florent Schmitt and Maurice Ravel. Later on, when he was much sought after as a teacher, he took only a few pupils, tutoring them privately. The best known of these was Darius Milhaud, who always retained a strong affection for and keen appreciation of his teacher, saying that some day his music would become far better known and appreciated.

None of these facts explains how or why the music of this man has remained so largely unknown, even to most musicians. This does not mean that Koechlin's music has been completely unperformed and his name a total stranger in Washington. Shortly after World War I, he was a guest of honor at a White House reception during the Post-World War I administration of Woodrow Wilson. And at least one of his songs appeared on a Phillips Collection years ago. That, however, is not much of a track record for a composer who has been correctly called "a key figure in the evolution of French music in the 20th century."

Part of the problem arises from the fact that Koechlin was not terribly interested in going any of the usual routes in promoting his own music. Of the more than 200 works that make up his output, only a few have been published. Some of these have happily found their way onto current recordings. The name of Antal Dorati stands high on the list of those who have performed signal services for Koechlin's music, since it was Dorati who made the first and only recording of one of the most significant, large orchestral scores: "Les Bandar-Log."

This is one of seven pieces Koechlin wrote based on Rudyard Kipling's "The Jungle Book." The "Bandar-Log" is the name Kipling uses for the jungle monkeys. In this music, scored for very large orchestra including two harps, piano and saxophones, Koechlin works to suggest a jungle scene in which the early morning calm is shattered by the chatter of the monkeys, those creatures which Kipling says are "the most vain and the most insignificant of creatures."

Some indication of the breadth of Koechlin's musical interests can be seen in other works of his that are also currently recorded: a partita for chamber orchestra, based on early dances; five chorals for orchestra, derived from medieval modal scale; a trio for flute, clarinet and bassoon; and, for those fortunate enough to own the recording, one of his songs sung exquisitely by Bidu Sayao.

Koechlin came to this country several times, including a visit to the campus at Berkeley, Calif, where he lectured and taught various classes. Had he operated as most of his colleagues did with regard to getting his music published and performed, those visits would have led to a far greater awareness of his writings in this country as well as in France. It is only in recent years that publishers and performers have begun to realize the true stature of this man whose symphonies include somewhat exotic titles like "The Seven Stars" and "Symphony of Hymns" in addition to those indentified purely by number.

This afternoon's Renwick concert will include three works in their U.S. premieres: a suite for flute, viola, violin and piano; songs for soprano, flute and piano; a quintet for flute, violin, viola, harp and something else. This last, numbered Op. 223, is one of the last work's from Koechlin's pen. The program will present music written over more than half a century.

In the 1979-80 season, conductor Eduardo Mata and the Dallas Symphony will give the U.S. premiere of the "Seven Stars" symphony. Perhaps Dorati can be persuaded to include "Les Bandar-Log" on his National and Detroit Symphony programs. With such stimuli, and today's Renwick concert, we would then at least have an opportunity of testing the opinion that Koechlin is "one of the outstanding figures in French music after Debussy."