Noxious chlorine vapors from a chemical spill forced the evacuation of the Madison Hotel yesterday but, in the tradition of most grand hotels, guests were escorted to its sister hotel and served coffee and tiny French pastries "on the house."

The spill, which originated in the basement of the 12-story luxury hotel shortly after 2 p.m., brought more than 80 firefighters to the scene. One person was seriously injured.

A laundry worker at the hotel, Jeanette D. Mickle, 49, of 44 K Street NW, was taken to George Washington University Medical Center after her clothes were permeated with the vapors. She was listed in fair condition last night, authorities said.

Women in furs and businessmen dressed in tweeds and pin-striped suits lined the sidewalks surrounding the hotel at 15th and M streets NW after the hotel and the Madison Office Building were evacuated.

Fifteenth Street was closed between L Street and Massachusetts Avenue and the 1400 block of M Street was blocked as 25 fire trucks and other emergency vehicles clogged the streets.

"I knew I didn't want to go to work today, but this is going a little too far," said a waitress at the hotel, one of about 100 employes who were forced to leave the building, according to Alfred Blackman, the hotel safety director.

Blackman said about 150 guests also were evacuated from their rooms and the hotel's restaurants and bars. Another 100 persons were ordered from law, consulting and research firms and other businesses with offices in the building, according to a spokesman.

But Madison officials were not about to let a little chemical leak and evacuation interfere with the niceties of life as guests were escorted to its sister hotel, the Dolley Madison, nearby on M Street, where white-coated waiters served tea and coffee and pastries on silver trays.

"This reminds me of the Riviera," said Agnes Shevcart, a hotel guest from St. Louis, as she sipped tea at the Dolley Madison.

Out in the lobby, under the fox-hunting prints, guests commended the hotel for grace under pressure. "They seem greatly embarrassed by this," said Robert A. Neal, a North Carolina businessman staying at the hotel, "and they're trying to make the best of it."

Employes, true to the hotel's privacy code, refused to say whether any of the famous, who often stop at the Madison, had been evacuated. "No, no, no. I can't tell you that," one employe said. "I want to still be working here tomorrow."

Fire officials said the the building was cleared as a "precautionary measure" after two bags containing about 70 pounds of a powdered chlorine laundry product stored on the floor of the third basement level were contaminated by water and started to emit dangerous vapors. A firefighter involved in the cleanup said the water appeared to have originated behind some washing machines nearby.