David and Goliath are hurling books at each other in the hushed aisles of your public library.

David is Richard D. Smith, who sees a big business opportunity in the millions of books that are crumbling because of damage caused by acid in the paper. Smith, a librarian and engineer, spent 20 years developing a nonaqueous liquid process to deacidify books. In 1972, he founded Wei T'o Associates Inc., of Matteson, Ill. (Wei T'o is the ancient Chinese god who protects books.) The Public Archives of Canada and the National Library of Canada have treated 20,000 books with the Wei T'o process since 1981 -- a pilot program that accounted for a significant portion of the company's $250,000 in sales last year.

The good news for Smith is that he has only one competitor he views as a serious threat. The bad news is that his competitor is the Library of Congress, which is probably the most influential force in the library world. The library developed its own process with public funds and will build a $11.5-million plant to treat a million volumes a year. Smith says comparable Wei T'o equipment would cost $1 million, mostly because it doesn't require a special facility to isolate toxic and explosively flammable chemicals. "In a fair competition, they wouldn't have the chance of a snowball in hell," he says.

Smith is more gentlemanly in academic journals, where the debate goes on oh so politely. But he knows it could be disastrous for him if the library licenses its own system, which it says is superior. "If you argue with the Library of Congress, it's almost like you're arguing with God Himself," explains Smith, who adds that three organizations are considering a Wei T'o facility.

"They may be winning a few battles, but they're not winning the war," Smith says. "I don't see any reason for an individual to back off from taking on groups in Washington just because they have access to the federal treasury."