Baltimore may have the Orioles, and New York the stock market, but here, everyone knows when the Capitol's cold marble starts echoing again. Nothing improves Washington social life like the return of Congress.

The 99th Congress was baptized yesterday and, before the gavel dropped on a single piece of legislation, it got down to the serious business of one gargantuan movable cocktail party. It won't be long before the 35 freshmen in both chambers learn where the true business gets done.

"It's a ni-ace building," said Rep. Tommy Robinson, the Arkansas sheriff-turned-congressman, in the best deep drawl he could muster. With that he moved quickly into the crowded Cannon House Office Building reception room, where under chandeliers the size of spaceships he smiled at the resounding applause that met him.

And so it went. From the chicken wings for 1,000 at New Jersey Sen. Bill Bradley's (D) party to the Boston baked beans waiting for Massachusetts Sen. John Kerry (D) to the dainty finger sandwiches in Senate Majority Leader Bob Dole's (R) suite, Capitol Hill came alive again with the clatter of confusion and a general anxiety that the blood of battle is once again hanging in the air.

"Hey, aren't you George Bush?" called out Sen. Patrick Leahy, a Vermont Democrat, at Dole's party.

It was.

"Absolutely," said Bush. That's all they said to each other.

"Call me if you have any good ideas," Bush implored Dole as he breezed through his office, and out the door. He never touched the chocolates.

"Oh, don't worry, I will," assured Dole.

At Sen. Paul Simon's (D-Ill.) party, the sight of the bespectacled face and signature bow tie brought a round of applause as the five-term congressman-turned-senator entered the room. Some supporters even sported tiny gold bow tie pins stuck on their lapels. Meanwhile, at the party for Arkansas' Robinson, not only did all the guests wear name tags but the congressman did, too.

This session brings to Washington a liberal Vietnam war hero from Massachusetts with the initials JFK, a Rockefeller (John J., who was not sworn in yesterday because he is filling out his term as governor of West Virginia), and a senator who inherited the legacy of his father. "I must say I got quite emotional," said Albert Gore of watching his namesake get sworn in to his onetime Senate seat. "I fought back the tears."

Presidential hopefuls four years hence were everywhere. Sen. Gary Hart and his wife, Lee, did their dutiful pass-throughs from office to office. When he was asked if he'd be around in six more years, he moved away, mumbling a faint: "We'll talk about that later."

And when Bill Bradley, another who has received The Mention, told his constituents how proud he was to tackle another six years in the Senate, one quipped, "Don't you mean four years, Bill?"

"It's six. You know that," snapped Bradley. He winked and walked away. The Dole Smooch

Liddy and Bob Dole, Washington's favorite political couple, took their first kiss in his new leadership office at approximately 1:30 in front of a crackling fireplace. No one missed it.

Dole's party for the entire Senate was definitely civilized, as pin-stripe suit after pin-stripe suit filed onto the thick maroon carpet to pay respects to the Senate's new highest ranking official.

Dole was in fine form, giving tours of his suite.

"Well, it looks like a furniture store now, but it'll get better," he explained. "We're getting some plants."

Tennessee's newly elected Democrat, Sen. Albert Gore, brought his mother-in-law.

"Oh, I want my picture taken with Mr. Dole," cried Margaret Aitcheson. "What a thrill of a lifetime!"

"Mother, you're from a Democratic family, now," chided Gore.

"Maybe so," she said, "but I'm for Dole in '88." Kerry's Klatch

You could call Massachusetts Sen. John Kerry's party a populist event. Or perhaps, a mob scene. Three hundred supporters overflowed the Dirksen party room, drinking champagne out of plastic glasses, and eating salami and baked beans.

"Awesome," said Kerry's mother, Rosemary Kerry. "Just awesome."

"A travel agent arranged it," explained Dick Stagnone, a 28-year-old computer programmer who worked on the campaign.

John Forbes Kerry is 41 and handsome and has the potential to become one of Washington's new darlings. A decorated Vietnam War hero, Kerry later vociferously opposed the same war. He also takes pride in the fact that his initials match those of his idol from the same state.

He was sworn in a full 12 hours before any of his freshman class, in a Massachusetts ceremony. "This one is more real," he said of yesterday's ceremony. "To be on the floor was just . . . well, it was moving. Sometimes, I just can't believe I'm here." Gramm and the Gang

Politicians can be smooth and graceful, but the true masters of the nonchalant attitude best befitting power are their jaded children.

"It's exciting, but . . ." said Marshall Gramm, the 11-year-old son of newly elected Sen. Phil Gramm (R-Tex.). Marshall let his voice fade from the "but" with just the right weary fall.

"We're kind of used to it," explained his brother, Jeff, 9, fiddling with his plastic glass so the ice inside jumped and chattered. "You can get tired," said Marshall.

Three hundred Gramm supporters had all come up to Washington to celebrate and, between the dinners and receptions, had "toured just about everything there is to tour in Washington," as Gramm's press secretary said.

"To me, it's important to finish one task before beginning another," said Gramm, "and this is really the concluding day of the election campaign to get here. These are the people who worked for 14 months, who did all the work that made this possible."

The people who made it possible, wearing distinctive blue name tags, could be seen wandering through the Capitol all day. They were, they said, very happy to be there. "At one point during the campaign we decided we were so excited that if he won we'd like to come up for the swearing-in," said Gramm supporter Bonnie Creel. Creel, a college instructor in Fort Worth, and her lawyer husband Jim have worked on all of Gramm's campaigns since 1976.

"It was one of the big thrills of my life," said Bonnie Creel about seeing the swearing-in in the Senate Chamber. "To be sitting there and see the very gracious and dignified way people conducted themselves, people I've always admired -- Nancy Kassebaum, Jesse Helms, Senator Strom Thurmond." Simon and Spouse

They met when they were both representatives in the Illinois state legislature. She was representing the North Shore (of Chicago) and he was from a southern Illinois district. That was 1957. Now, he's a new senator and she was standing in the middle of a Russell Senate Office Building caucus room, excitedly waving the congressional ID tag that hung around her neck and read "SENATE (Spouse)."

"I'm a Senate wife, and I'm so proud to wear this," said Jeanne Simon, spouse of the new senator, Paul Simon, a Democrat. He was wandering the room, shaking hands, bow tie in place. She, tall and handsome, was wearing a red dress with a tiny gold pin shaped like a bow tie. She's also a lawyer, and she gave up her Illinois legislature seat in 1960 when they got married. "Maybe, today things would be different, but that's the way we did things in 1960," she said. "I have no regrets, because I knew Paul was very special."

In the room were their two children, who stood up and yelled when Simon was sworn in. "They're going to take down Ben Franklin's statue and put up Dad's," 20-year-old Martin Simon predicted as his sister, Sheila, 23, laughed.

The room was overflowing with unabashed good cheer for the well-liked, former five-term congressman who first came to Washington in the 1974 Watergate class. "I was probably the only black alderman in Chicago pre-primary to support Paul Simon openly," said Perry Hutchinson, adding that Simon eventually got more than 80 percent of the black vote in the Chicago area. "Looks like I was correct this time."

The new senator swept by, all smiles. "I'm old-fashioned enough," he said, that "I get excited just seeing the Capitol every day." First-Day Resolution

Freshman Rep. Joe Barton (R-Tex.), who has taken new Republican Sen. Phil Gramm's former seat, beamed at a reception as he told friends how he had just marked his first day in Congress by introducing his own bill -- a balanced budget resolution. "I just did it! I put it in the hopper," he said.

Barton, a former petroleum engineer who has a friendly, low-key manner, said that, although he is for a strong defense, it "will" be necessary to cut the defense budget. His 2-year-old daughter, Kristin, clung to his left leg as he spoke. The Bartons have three children, and Janet Barton considers taking care of them full-time work: "I've been busy being a homemaker." The Mass From Maryland

Democratic Rep. Beverly B. Byron's western Maryland district is close enough to Washington so that hundreds of her constituents came in busloads from Frederick, Hagerstown and points west to attend her reception in one of the largest hearing rooms in the Cannon Building.

Byron, who chairs the House Armed Services Committee's panel on arms control and disarmament, is intensely interested in Secretary of State George Shultz's upcoming meeting in Geneva with Soviet Foreign Minister Andrei A. Gromyko.

"The fact that we're back at the table meeting is a very great step forward," she said. "I hope the expectations of that meeting aren't so high that people will be disappointed." In Ferraro's Place

Freshman Rep. Thomas J. Manton (D-N.Y.) won the Queens seat vacated by Geraldine Ferraro when she decided to run for vice president. New staffers and friends gathered yesterday at Manton's new office in Room 327 of the Cannon Building.

"Many of the people here are Ferraro supporters going back a long time," said Manton's new chief of staff, Walter McCaffrey, "so it's a bittersweet situation." Ready to Roll

Clumps of discarded paper plates and plastic cups lay on the tables at the party for Tommy Robinson (D-Ark.) in the Cannon office of chief deputy majority whip Bill Alexander (D-Ark.). But the new congressman was just getting going.

"I don't have sweaty palms," said Robinson, the former sheriff of Pulaski County. "There won't be any bridges or hospitals or roads named after me. I'm dedicated to reducing the national debt." Reporters were beginning to gather round.

"I see this as a very trying time," Robinson said. "I'm devoting myself to seven days a week, 18 hours a day. I want to know about every piece of legislation that crosses that floor."

Robinson already has a draft of a bill he wants to introduce. In Arkansas this spring a federal judge ordered the three school districts of Pulaski, the state's largest county, consolidated to further integration. Robinson's bill would prevent federal courts from ordering such consolidation before trying other "less drastic plans" -- such as moving just a few schools from one district to another -- as Robinson aide Darryl Glascock put it.

"I'm going to try to stop federal courts from ordering schools to consolidate on the whim of a federal judge who decides he doesn't like the ratio," said Robinson. "No one can have perfect demographics."

Reporters were earnestly scribbling.

"He's somewhat like Andrew Jackson," observed Lloyd Rutledge, who lives in Virginia and farms in Arkansas. "He isn't typical of the Washington scene."