Last April, two paintings by William Bouguereau helped Sotheby’s bring in $20 million during its 19th-century European art sale, a remarkable surge for a category that had cruised along with sales of $7 million to $8 million for the previous five years. When Sotheby’s holds its 19thcentury sale next week, it will have five Bouguereau paintings on offer, and the entire sale is estimated at $16.8 million to $23.5 million.

“Bouguereau is certainly an artist whose performance indicates general strength in that market,” Fred Bancroft of Salander-O’Reilly said. “The fact that he is selling well is an indication of the fact that the auction house expectations are generally within reason and that the market is healthy.”

Bouguereau (1828-1905) was popular during his own lifetime, but along with many other late-19th-century painters, he fell out of favor in the mid-20th century. New Jersey collector Fred Ross, who runs the Web site artrenewal.org and owns 13 Bouguereaus, said that when he started buying in 1977, Bouguereau works could be had for $10,000.

“You can’t be too rich, too thin, or have too many Bouguereaus,” said Mr. Ross, who is compiling the artist’s catalogue raisonne with Damien Bartoli.

The Bouguereau works at Sotheby’s portray milky white women, either caressing naked babes or displaying their own comely body parts, with estimates ranging from $40,000 to $800,000. Christie’s, which also holds its 19th-century European art sale next week, is selling a Bouguereau of the melancholic muse Philomela: The 1861 canvas is estimated at $250,000 to $350,000. Christie’s sale is expected to bring in $16.3 million to $24.4 million.

Another popular 19th-century portrait painter is Giovanni Boldini, whose prices have ticked upward since the sale of 15 of his portraits by Baron Maurice de Rothschild in 1995. Boldini’s full-length portraits, mainly of women in soignee evening dresses, are in the same class as those by John Singer Sargent or Anders Zorn. The head of Sotheby’s department of 19thcentury paintings, Polly Sartori, said she chased down more portraits by Boldini after Sotheby’s sold three from the HSBC collection a year ago, when the paintings doubled the prices the bank had paid for them at the Rothschild sale.

“Boldini and Sargent were so out of fashion in the ’50s, ’60s, ’70s,” said Gregory Hedberg of Hirschl & Adler Galleries, “that you could buy them for practically nothing. Now they both parallel a return to fashion. People are really looking at portraits.”

Of course, it helps if the portrait is of a pretty woman,and the two Boldini portraits leading Sotheby’s sale this season are of lovely ladies. Both come from the Rothschild collection sold in 1995. “The marketplace is being exposed to these for the first time,” Ms. Sartori said. “Portrait of Donna Franca Florio” (1924) is estimated at $800,000 to $1 million. If it sells within the estimate, it will fetch three times its 1995 price of $382,000.

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Curious about the state of the European economies? The 19th-century sales offer an informal gauge.

The sale category is broad enough and the buyers patriotic enough that fluctuations in national wealth can impact sale totals. Nearly giddy with cash, the Russian rich, in particular, are expected to remain bullish for landscapes by painters such as Ivan Konstantinovich Aivazovsky, a seafaring Turner acolyte.

Christie’s divides its catalog into national categories to make the point clear. The regions listed in the Christie’s sale are a reminder of who ran the world in the 19th century: Scandinavians, Greeks, and Russians; Germans, Austrians, Dutch, and Belgians; Victorians; Italians and Spanish; and the French. “The thing about 19th-century is, it’s actually a lot of different markets: German, Barbizon, Spanish,” Christie’s head of 19th-century paintings, Deborah Coy, said. “This enables us to see which markets are moving.”

A separate group of Orientalist art, images of Arab and North African society made by Europeans, opens the Christie’s sale. It is estimated to bring in $3.6 million to $5.4 million. Middle Eastern buyers make up a good proportion of collectors for exotic images of their own palaces and bazaars, but Ms. Coy said Orientalist art appeals to a broad base of American and European collectors because “the colors are strong, it’s great light, and the subject matter is intriguing.”

Even the paintings that are not explicitly Orientalist reflect a world poised between romantic visions of unspoiled neoclassical paradises and a new, frenetic pace of global trade. Oranges from the Southern Hemisphere and flags from ships hailing from ports around the world pop up in multiple paintings from nearly every nation.

James Jacques Joseph Tissot’s “A Fete Day at Brighton” (c. 1876-77) at Christie’s holds the highest estimate of the week’s sales at $3 million to $5 million. It shows the love of his life, Kathleen Newton, striding down a street in Brighton, flags billowing behind her.