"This web site has been developed in the frame of a research project whose purpose consists in the identification and valorization of printed material and manuscripts relevant for the history of chemistry preserved in three Spanish institutions, the libraries belonging to Spanish Research Council (CSIC); the "Marqués de Valdecilla" Historical Library of Universidad Complutense (UCM) in Madrid, and the Spanish National Library. This project, which was launched in 2005, has been made possible thanks to the continuous financial support of the former Spanish Ministry of Education and Science, and the actual Ministry of Science and Innovation. Preliminary results of this project have been presented in several national and international conferences, but the main outcome of it consists in this on-line Historical Chemical Library."