September 18, 1986

AFTER nearly three decades of neglect and abuse, Art Nouveau architecture in Brussels -one of the style's capitals - is undergoing a renaissance. Connoisseurs of Art Nouveau, the curving floral style that had its heyday at the turn-of-the century, are restoring the remaining buildings of the architect Victor Horta, the movement's pioneer in Belgium. Horta's distinctive style caught the attention of other European and British designers: Brussels became one of the principal centers of Art Nouveau because of Horta's presence there. Before his death in 1947 at the age of 86, however, Horta saw his work, and that of his many followers, fall victim to the wrecking ball. The iron beams that lost their coldness in curving, lyrical designs were sold as scrap metal and the stained glass windows that turned a dull view into a festival of changing colors were being destroyed.

International A bomb killed five Parisians and wounded 50 in front of a crowded department store on the Left Bank. The police said the bomb had been hurled from a passing car in the most deadly of five terrorist attacks to shake Paris in 10 days. The bombing occurred despite a general mobilization of security forces and an intensive police hunt for those responsible for the terrorism. [ Page A1, Column 6. ] The bombing stunned Parisians more than the previous four attacks and generated panic in a city celebrated for its civilized openness. A taxi driver of Arab origin, dazed by the carnage on the Rue de Rennes, exclaimed, ''My God, it looked like Beirut. Beirut on the Seine.'' [ A1:5. ]

The owner of the Collingwood Hotel in midtown Manhattan announced yesterday that he would not permit the city to house 200 homeless families in his hotel - a move that will place added pressure on the city's overburdened shelter system. An advocacy group, the Coalition for the Homeless, meanwhile, said that it would oppose any move to put homeless families into shelters used by single men and women because its survey shows all of those shelters are now at or over their legal capacity. And on Staten Island, residents turned out to oppose the city's plan to open an emergency family shelter in their borough. Richard Foreman, who described himself as the ''sole stockholder, owner-operator'' of the Collingwood, said in an interview that he had decided the hotel would continue to serve tourists, rather than become a center for welfare families.

At a news conference today packed with enough photographers for a Cecil B. De Mille production, the actor Paul Newman outlined his vision for a rustic Western village - ''a turn-of-the-century lumber camp in Oregon'' -that is to rise from 300 acres of forest in northeastern Connecticut. But this village, which is to have log cabins, corrals, a music hall and a saloon with swinging doors, is not going to be one of Mr. Newman's make-believe movie sets. Instead, it is to be a real-life summer camp for children who are battling leukemia and other forms of cancer. ''This is made possible by salad dressing, and by the people who buy the damn stuff,'' Mr. Newman told reporters gathered at the Yale-New Haven Medical Center here. He was referring to one of the products of his flourishing food company, Newman's Own, which began as ''a cottage joke'' four years ago. The actor has pledged $4 million in profits from the company to the camp, expected to cost about $8 million to build and endow. Mr. Newman said that the remaining money will be raised through corporate and individual donations.

Caution prevailed on Wall Street again yesterday, as stock prices were mixed for the third straight session. But there was a slight change over the previous two days, as investors bought secondary issues, while selling blue chips. On Monday and Tuesday, the opposite happened, causing the blue-chip Dow Jones industrial average to move up slightly, while the bulk of the market retreated. Yesterday, it was the Dow that fell, by 9.14 points, to 1,769.40. Despite the drop, market experts say there is no clear trend emerging on Wall Street, where stock prices were battered last week by a combination of internal market factors and concern about interest rates.

The United States said today that it had given Moscow a list of 25 members of the Soviet Mission to the United Nations who must leave by Oct. 1. This is the largest number of Soviet diplomats ever expelled by the United States at one time. The White House and the State Department denied that the action was in retaliation for the restricted status in Moscow of an American journalist, Nicholas S. Daniloff, who is awaiting a possible trial on espionage charges. The American step, officials said, is aimed at making make sure that the Soviet Union complies with an order of six months ago to reduce the size of its United Nations missions. Move to Show U.S. Toughness But a White House official said the decision to expel the 25 mission members and to do it in a publicized way was related to a desire to appear tough and to show that the United States was ready to put into effect retaliatory measures until Mr. Daniloff is given safe passage back home.

The New York City Board of Education, for the first time asserting control over admissions to the city's high schools, voted yesterday to ease the entrance requirements for eight career-oriented schools and for more than 100 career programs at 52 other high schools. Board officials estimated that about half the 62,000 freshmen next year would be affected by the changes, which include random selection for 50 percent of the entering class in these schools and programs. The changes, the first major policy decision of the newly constituted board, do not apply to the city's four specialized high schools - Stuyvesant, Brooklyn Technical, Bronx Science and the Fiorello H. La Guardia High School of Performing Arts. A Personal Triumph Until now, the eight career-oriented high schools - which have come under fire from civic groups, some board members and the new head of the high schools division, Dr. Frank L. Smith Jr., for being too exclusionary - have handpicked their students within loose guidelines provided by the board. There has been no random selection at these schools.

One of the news broadcasts tonight opened with an anchorwoman saying, ''It was the kind of night when we would prefer not to have had television news.'' Then came the footage of the carnage from the bombing on the Rue de Rennes - blood splattered on the normally impeccable Parisian streets; bodies strewn along the sidewalk; abandoned coats and other clothing; the screams and wimpering of children mixed with wailing police sirens; shattered glass, glistening in light rain in the twilight. ''It looked like the aftermath of an air raid,'' the announcer said. 'Beirut on the Seine' A French taxi driver of Arab origin who was caught in the bumper-to-bumper traffic near Tati department store, the target of the attack, had a different impression.

The Economy The Fed may resist a further cut in interest rates until it can get a better reading of new inflationary signs, the board's vice chairman suggested. In remarks to economists, Manuel H. Johnson also said he might support some temporary, and unspecified, ''approach'' to ''redress the imbalances in the domestic and world economies.'' [ Page D1. ] Credit markets were little changed. Prospects that central bankers in West Germany and Japan will reduce interest rates appear to have faded, but traders continued to believe that further declines in American rates are possible. [ D21. ] Housing construction edged up 0.4 percent in August after three consecutive declines, but analysts said the pickup, to an annual rate of 1.82 million units, did not signal a return to boom times. [ D8. ]

LIFE without Baggies. It's not quite fodder for a post-nuclear disaster movie, and certainly, the fate of the earth does not hinge upon them. But for consumers, plastic Baggies are one of those little things that make a difference in daily life. Without them, Betty Furness would have a tougher time toting pickles and sliced steak leftovers to the office, and Leona Helmsley would have to find substitute storage for her homemade chicken with pesto or marinara sauce. Each year, according to Consumers Union, 2,000 to 4,000 new consumer products appear in the American marketplace. Many are simply the effluvium of a hyped-up consumer culture, yet another thing to make us fret about waxy buildup or unwanted hair. But a few, as seen in the forthcoming exhibit ''Milestones: 50 Years of Goods and Services'' culled by Consumers Union for its 50th anniversary, opening at the Cooper-Hewitt Museum on Sept. 23, have been downright earthshaking - big deals that have affected the lives and attitudes of hundreds of millions of consumers.

Come the ''triple witching hour'' Friday afternoon, financial wizards will pay as much attention to the Chicago futures trading pits as to the stock exchanges in New York. For while the stock plunge on Wall Street last week got all the attention, the action in Chicago's futures markets was just as furious - and one of the main lessons was that the Chicago traders help shape what happens in New York. ''If you take a look at the way the market jerks around in a day, it's hard to conclude that index futures contracts are not having a major impact on the volume and volatility in the equity marketplace,'' said B. Macon Brewer, chairman of the capital markets division of Dean Witter Reynolds Inc. Stock index futures are contracts, bought and sold, that represent a bundle of underlying stocks. They go up and down with the stock market and enable investors to speculate on broad market rises and hedge against market falls. Often, futures prices swing more violently than the underlying stock prices because futures traders seek to anticipate market swings.

The Senate tonight confirmed William Hubbs Rehnquist as the 16th Chief Justice of the United States and Antonin Scalia to succeed him as an Associate Justice. The vote on Justice Rehnquist was 65 to 33. The vote on Judge Scalia, now a judge on the United States Court of Appeals for the District of Columbia, was 98 to 0. Senator Jake Garn, the Utah Republican who is recovering from surgery, was absent, as was Senator Barry Goldwater, Republican of Arizona. Forty-nine Republicans and 16 Democrats voted for Justice Rehnquist, with 31 Democrats and 2 Republicans voting against him.