Deep in the climate-controlled, underground recesses of John Hopkins University's Milton S. Eisenhower Library, hundreds of thousands of aging books stand on modern steel shelves, their pages silently turning too brittle to touch.
Printed over the past two centuries on paper that is highly acidic, an estimated 90 percent of the research library's 2 million volumes are in danger of becoming unusable, their content lost as their pages slowly decay.
"It's already a very large problem," said library director Scott Bennett. "Thirty percent of what we now own is so brittle it can't be safely used."
Library technicians are nibbling at the problem by photocopying or microfilming the most valuable and threatened books in the collection. But that can cost up to $70 per book, and the technicians' piecemeal efforts are being outraced by time and the sheer scale of the problem.
Yesterday, in a bold effort to get ahead of the decay, Bennett signed a one-year, $40,000 contract with Netherlands-based Akzo Chemicals Inc., to begin de-acidifying salvageable portions the library's collection on a large scale, using a new gas technique at a cost of $11 each.
"To my knowledge, we are the first research library in the world to undertake commercial mass de-acidification," Bennett said.
Time is running out for millions of irreplaceable books, Bennett said. "Sixty percent of research library collections throughout the nation are printed on paper that is acidic, but not yet brittle."
The Akzo process will stop the acid damage, but can't reverse it. Books already crumbling at Hopkins will have to be copied to be saved. But newer books in danger of becoming brittle in decades to come will be preserved.
"Our data says high-quality paper can last 500-plus years and still be flexible" after treatment, said Richard F. Miller, Akzo's director of book and document protection. Cheaper wood-pulp paper should last "several hundred years."
Starting next month, Akzo will treat about 350 books from Hopkins' collection each week at a facility near Houston, using a process developed by the Library of Congress and licensed to Akzo.
In all, Bennett hopes that 4,000 volumes can be treated during the first year of the contract, starting with new foreign-language books from overseas where acid paper continues in wide use.
That's barely 10 percent of the Eisenhower Library's annual list of new acquisitions. It doesn't begin to touch the old books already decaying on the library stacks.
"But we've got to make a beginning," Bennett said.
Hopkins and Akzo hope that the contract -- Akzo's first -- will keep the Houston processing center operating and attract enough new business to bring down the cost.
"We think it will snowball very quickly," Bennett said.
The Akzo process has been shown in animal tests, to Hopkins' satisfaction, to be effective and safe for Akzo workers and
people handling the treated books.
Miller acknowledged that the chemical industry "is not well-regarded in the popular press. . . . Our image is part of the reason we're doing it."
The problem of acid paper is one that threatens book collections all over the world.
Beginning in about 1800, the explosive growth of literacy and book publishing led manufacturers to turn from more durable paper to less-expensive paper made from wood pulp, using processes that left the books highly acidic.
"They wanted to make them fast, and they wanted to make a lot of money, and they had all these trees," said Ellen Stiffler, a Hopkins spokeswoman.
As early as 1826, however, book owners began to recognize that the acidic paper would not last.
Bennett said the cellulose molecules, normally 10,000 carbon atoms long, give paper its flexibility and strength. But acid eventually breaks them into fragments only a few hundred atoms long, leaving the paper brittle.
Holding a page from an 1887 edition of R.B. Haldane's biography of Scottish economist Adam Smith, Bennett curled his fingers. The paper broke into hundreds of sharp-cornered fragments that fell from his palm like confetti.
"It's like a brown country eggshell," Stiffler said.
Fortunately, Bennett said, more than 80 percent of printing paper made in this country is now alkaline-based and resistant to decay.
Thanks to that change, the acid paper problem "may have a finite time span," he said. "What's unhappy is that time span is 200 years," a period during which all the development of the modern world was recorded in printed form.
The books sent to Texas for deacidification will be placed, 350 at a time, in a 6-foot cylindrical chamber.
After the air is drawn out of the chamber, a highly volatile gas called diethyl zinc will be pumped in, penetrating the pages of the closed books. Over 2 1/2 days, the gas will both neutralize the acid in the paper and form an alkaline "buffer" to ward off future damage by acidic air pollutants.
The books will be out of circulation for three weeks, Bennett said. Treated books do not look or feel any different from untreated books.