To see pictures of Evelyn Nesbit in her glorious guises -- coquette, vamp, sophisticate -- is to understand how whe was able to shake turn-of-the-century society. (The trials of her jealous husband, Harry Thaw, for the 1906 murder of architect Stanford White were the sensation of the decade.)

Nesbit steals the scene at the Museum of American History's new exhibit, "Platinum Women." The 52 "fashionable women," including Mrs. John Jacob Astor and Mrs. Harry Payne Whitney, posed for three prominent New York photographers: Rudolf Eickemeyer Jr., Gertrude Stanton Kasebier and Clarence White.Beyond the photographers' artistry and the women's beauty and bearing, the underlying subject of the show is the photographic process itself. Platinotypes, portrait photographs on platinum paper, were forerunners of today's silver-image paper.

The process was patented in England in 1873, and was popular until costs became prohibitive, forcing Eastman Kodak and other manufacturers to switch from platinum by 1916.

These gorgeous prints from the Smithsonian's collection demonstrate the platinotypes' winning way with fine lines and sensual textures in tones from blueish grays to warm browns. Delicate details show through dark shadows; the softness of the subjects is mirrored by the process.

Of the 1980s look of some of the faces, curator Eugene Ostroff says, "The image lives for us, that's what a good photographer will do." It's the camera's affinity for its subjects that renders a timeless shot. But props (garlands, hats, pearls, furs, a palm frond) and poses (Astor's heavy-lidded eyes and Nesbit's moue ) convey the grace and gentility of an era extinct.

A related photographic show, "Generations of Women," opens Friday at Market 5 Gallery, in the Eastern Market building. A women's studies program at Jersey City State College turned up the more than 80 prints of the students' female forebears. These aren't posed portraits of aristocrats, buy family-album snaps of young and old women of sundry ethnic, class and national backgrounds. The sepia and black-and-white print enlargements (some blown up to 4-by-8-foot panels), date as far back as the 1860s, though most fall into the half-century between 1890 and 1940.

Professor Barbara Rubin, who coordinated the show with Dr. Doris Friedensohn, said students documented "the story lines behind the facial lines." The photobiographies are grouped in five categories: portraits, romance, friendship, motherhood and occasions.

The organizers wrote, "We were seeking their likenesses, their loved ones, the objects they held dear and the ordinary possessions which marked their time and place . . . We wanted to tie the present to the past."

PLATINUM WOMEN: At the National Museum of American History's third-floor Hall of Photography. Opens Friday, continuing indefinitely.; GENERATIONS OF WOMEN: PRIVATE LIVES: At The Market 5 Gallery, Seventh and North Carolina Avenue SE, opens Friday, through July 5.