Appiah said Time Warner CEO Gerald M. Levin's interest in public service contributed to the purchase.

"A philosopher-king is slightly overblown, but he's someone who really does believe that an important part of the responsibility of large corporations is giving back to the community," he said.

But Gates' colleagues said the acquisition will ultimately make Time Warner money.

"They're interested in the overall enhancement of their product," said Al Holman, a venture capitalist who collaborated with Gates. "My experience tells me that if you do that right you make money too."

Online business experts said Time Warner may hope to use the site to capture black web users.

"With a monolithic organization like Time Warner, it's not going to give them any significant incremental profit, but it will certainly complete a product," said Cooma Chelliah, Senior Vice President of britannica.com, the online site of Encyclopedia Britannica.

From the Yard to Wall Street

Gates and Appiah launched the site on Martin Luther King's birthday in 1999, largely to sell copies of the Africana encyclopedia on CD-ROM and in print.