Chinese Export china from a large and important Washington collection boosted total sales at the C.G. Sloan & Co. auction last weekend to $955,000.

The china itself, a hot item currently on the antique scene, brought $52,000, including a covered butter dish for $1,400. Donald Webster, a co-owner of the auction house, said that the china, from the 18th century and earlier, brought people here from all over the country. A notable number of foreign buyers, especially Japanese and Germans, are currently turning up at Washington actions, spurred by the favorable money exchange.

The auction grossed about 15 to 20 percent over Webster's pre-sale estimates. The only disappointments were the comparatively low prices brought by rugs and jewelry.

The next catalogue auction at Slean's will be May 31-June 3. Highlights include the Rembrandt Peale "porthole" portrait of George Washington, a T'ang Dynasty ceramic camel, an Alexander Roux inalid card table, paintiings by Philip Van Dyke (Flemish, 1680-1753) and William Merritt Chase (American 1849-1916), and a suite of diamond and sapphire jewelry with diamonds totaking 51.04 earats in weight.

Adam A. Weschler & Son will bold its next catalogue auction May 18-20 with consignors including an East Coast museum. Among the items are a Sheraton carved mahogany sideboard, attributed to Nehemiah Adams of Salem, Mass.; a collection of Chinese carved jade; a silk and matallic Tabriz bird and garden rug, and a painting by Eugene Louis Boudin (French, 1824-1893). A group of cameras and pocket watches, from the immense and varied Owen H. Ramsburg collection, also will be offered for sale during this auction.

In New York, Sotheby Parke Bernet's great Benjamin Sonneberg Collection will be auctioned June 5 through 9. The collection is so immense that it takes two catalogues to describe it, one for paintings, drawings and sculpture and the second for furniture and other works. Among the most important pieces are a pair of English white marble portrait busts by Joseph Nollekens (late 18th century); a pair of George II silver-covered jugs by Humphrey Payne (London, 1732), and paintings by Cassatt, Cezanne, Daumier, Gaugin, Renoir, Vuillard and others.