This collection by Yale University’s Beinecke Rare Book and Manuscript Library focuses on alchemical literature from Europe. Despite the title, I found objects from as early as 1400 and none from later than 1790. I couldn’t find specific information about the collection development policy, although this may be explained by the front-page announcement that: “Many of the items available here are drawn from the exhibition Book of Secrets: Alchemy and the European Imagination, 1500-2000, January 20 - April 18, 2009, at the Beinecke Library.” This may also answer the question of who the intended audience is (i.e. exhibit attendees).
The objects in the collection are really interesting and beautiful to me, with a variety of printing types represented. All scans I checked were 400ppi .jpg files with no apparent watermarks or copy protection, and the layout is simple and functional. The metadata is comprehensive, with notable fields such as “Physical Description” giving objective attributes of objects (though dimensions were missing for some objects) and wonderfully unexpected (if sometimes non-sequitur) information in the “Note” and “Summary/Description” fields of many objects. There is also info providing a clear path for finding the source objects in the collection.
The representation of objects in the collection is inconsistent. Some are scanned as full manuscripts, with covers and all pages represented, while others are scanned selectively, seemingly with a focus on pages with images. It would be nice to know more about their decision making processes. Although this collection currently exists as a supplement to an exhibit, it is not far from standing on its own as a digital library. With the Book of Secrets exhibition currently in progress, there is hope that future updates could add the information to help accomplish this.