If you have torn yourself away from the virtual library that is the Internet long enough to visit a real library, you know that the smell of old books -- musty, slightly acidic, even grassy -- is instantly recognizable. But is it quantifiable? And if so, might old-book odor prove useful to librarians and conservators charged with preserving collections? Matija Strlic, a researcher with the Center for Sustainable Heritage at University College London, thinks it might. With colleagues in Slovenia and with the assistance of the National Archives of the Netherlands, he has published proof-of-concept research that shows that it is possible to understand both the composition and condition of old paper by analyzing the volatile organic compounds they emit. [ABSTRACT FROM PUBLISHER]