The talk last night at the Washington Antiques Show, appropriately, was about the recent sale of Washington's oldest house, The Lindens, to Norman Bernstein, a local financier, and his wife.

The Bernsteins reportedly paid in the neighborhood of $1.5 million--somewhat less than the asking price of $1.9 million.

The future of historic The Lindens had been imperiled since the death of its owner, Miriam Hubbard Morris, June 3. The house built in 1754, in the heart of posh Kalorama, was put up for sale after efforts to preserve it as a house museum failed.

Last night, informally fielding questions about the sale of The Lindens were White House Curator Clement E. Conger, who had tried to establish the house as a museum; Richard Howland of the Smithsonian, a well-known Washington architectural historian, and Hope Ridings Miller, author of "The Great Houses of Washington."

According to them, the Bernsteins plan to live in the house and have asked Walter Mayo Macomber, the former Williamsburg architect who supervised the move of the house from Danvers, Mass., to Washington in the 1930s, to help them restore it.

Bernstein, who is president of Guardian Federal Savings and Loan and of Columbia Realty Trust Co., apparently intends to preserve all the house's remarkable stenciling but will not start with the sort of museum quality antiques that Morris had.

The Lindens, under Morris, was a treasure house of American antiques. Many are being sold in an auction scheduled later this month at Christie's in New York and are expected to bring about $2 million.

But The Lindens was not the only thing on the minds of the 800 guests who paid $85 each to attend the invitational reception, dinner and preview last night at the Shoreham, which benefited The Thrift Shop Charities. They got the first chance to buy from the 44 dealers at the 28th annual show.

Chief of Naval Operations James Watkins spent 15 minutes at the Marine Arts Gallery booth, entranced by a painting of a ship by Alexander Stuart of Delaware. Watkins and his wife live in the historic Tingey House in the Navy Yard in Southeast. A group is now trying to add to the historic house's antique collection.

At booths throughout the hall, incense burners were a big item. There were Staffordshire ceramic burners made in the shapes of small cottages, Chinese temples and castles, and prices ran from $385 to $485. "We can't keep them in stock. There's a big revival," said a dealer at the Good and Hutchinson booth.

Katherine Sellers of Katherine Denny booth said silver, which had been depressed in price, is now selling briskly. "We've already sold an enormous pair of candlesticks tonight."

The show was full of high-ticket objects such as the Japanese silver and brass on wood carved saddle (1846), offered for sale at $5,000 by the E. J. Frankel booth, and a Chinese settee with heavy organic carvings offered at $4,500 by Frank Schwartz.

Most of those picking up and laying down objects in the exhibition hall fit the description of the Baltimore grande dame who is alleged to have said, "One doesn't buy antiques, one inherits antiques."

Even so, the guests, many of them old Washington families, looked carefully at the elegant Federal period antiques spread through the hall.

For some, the evening was a chance to find the Chinese Export porcelain saucer to match great grandmother's set. For others, it was the opportunity to see how prices are holding up on their own antiques by comparing dealers' prices on say, a Hepplewhite chair with the one at home. The dealers, specialists in pre-1830 antiques, come from all over the Eastern Seaboard, offering more inducements to spend money.

Nancy Reagan, who did not attend, was honorary chairman of the show. The working chairwomen, Olive Cobb and Annette Lasley, were trying to be everywhere at once last night, and very nearly succeeded.

And Clement Conger was especially popular--he lent the show's exhibition of 29 priceless pieces of American Federal period furniture ornamented with eagles. The eagle furniture normally is housed in the James Madison dining room and the James Monroe reception room, the secretary of state's intimate entertaining suite in the Diplomatic Reception Rooms.

Conger and his wife, Lianne, always stop first to look at the Chinese Export porcelain. They often buy a piece to add to their collection--and this year bought a soup tureen and two plates from Elinor Gordon, the doyenne of the Chinese Export porcelain.

Each of the two dinner sittings were full, according to cochairwomen Ursula Quin and Jane West. The show will be open from noon to 9:30 p.m. today through Saturday and from noon to 6 p.m. Sunday.