FOR SOMEONE considered to be a flamboyant dandy, James McNeill Whistler did a lot of work. We now learn, through a show of 84 lithographs on display at the Smithsonian's Museum of American Art, that he greatly advanced lithography in his years of experimenting with it.

That may be esoteric, but the exhibit isn't. With last year's ultimate Whistler show at the Freer still lingering in memory, we can seek out his images as expressed in this medium. The lithographs compose a gentle reprise.

Lithography means writing on stone -- with greasy crayon or pencil, taking advantage of the natural antipathy of grease and water to finally produce a print on paper. Whistler generally used an additional step, making grease drawings on lithographic transfer paper instead of directly on the stone. This way, his pictue didn't come out reversed.

And this way, the American expatriate could wander the streets of Chelsea or Paris with paper, making quick studies of shopfronts and storekeepers: the clockmaker, the laundress, the blacksmith, the rag merchant and the fish seller.

He outlined the arch of a doorway in the courtyard of Chelsea Hospital, and the symmetrical depth down the long darkened corridor inside. Whistler liked these architectural details -- but not as much as he enjoyed portraying the frills of fashion -- leg-of-mutton sleeves, ruffled long skirts. In his intimate family portraits, of his wife and his sister-in-law, faces are obscured but details of dress emphasized.

Then, too, the lithography process doesn't produce exact portraiture: The fine, velvety lines tend to disappear, leaving only form.

Most exciting in the show are two landscapes Whistler produced by lithotint, a wash variation of lithography. Done early in his experimentation, somewhere between 1878 and 1887, a "Nocturne" is more Whistlerian than the famous Whistler seascapes in oil. For with this dark wash, the moody harbor scene of a lone fisherman on a boat becomes all the color of fog.

Much later, in 1896, Whistler tried the lithotint again, painting a magnificent view of the Thames from rooms on the top floor of the Savoy Hotel. With its two-dimensional treatment of pattern, the lovely scene is like the Japanese screens Whistler so admired.

Whistler spent some months at the Savoy with his adored wife Trixie, who was dying of cancer. There, besides drawing the Thames from the window, he also did two lithographs of the bedridden Trixie, who had greatly encouraged him to pursue lithography. One he called, hopefully, "La Belle Dame Convalescent." But she was to die within a few months.

LITHOGRAPHS OF JAMES McNEILL WHISTLER -- At the Museum of American Art through August 18.